Physics Midterm Exam

Regular Class 2 Mr. Tran
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Terms in this set (...)

Is Speed a Vector or Scalar Quantity?
Vector Quantity
What are the two measurements needed for calculating average speed?
Distance and Time
If a car is moving 40km/h and it turns a corner at 40 km/h, does it ___
maintains constant speed
If someone gave you the total distance traveled on the trip and how much time if took for them to get there what can you determine?
Average Speed
30km/min is measuring what?
Speed
A horse gallops a distance of 10 kilometers in a time of 30 minutes. It's average speed is ___
20km/h
A car maintains a constant velocity of 100 km/hr for 10 seconds. During this time interval its acceleration is ___.
Zero
A car accelerates at 2 m/s squared. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 30 m/s? Identify the equation you need to solve the problem.
s= a*t
A heavy object and a light object are dropped at the same time from a rest in a vacuum. The heavier object ___.
at the same time as the lighter object
What object has a greater acceleration- the heavy or light object?
both objects have the same acceleration
It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
about 60m
While an object near the earth's surface is in free fall, its _____.
velocity increases
If a car is moving 40km/h and it turns a corner a 40 km/h does it _____.
maintains constant speed
When an object is thrown upward, what force is slowing down the object?
Gravitational Force
The SI unit used to measure Acceleration is ___.
m/s^2
Can an object move when its acceleration is zero. Justify your answer?
Yes-- An object accelerates when it becomes faster than its previous speed. But an object can move at a constant speed and have no acceleration.
Distinguish between speed and velocity. Give an example of each.
Speed only tells how fast an object is going. An example of speed would be 60mph. Velocity tells speed and direction. An example of velocity would be 60mph North.
What would be the difference in dropping an elephant and a feather off a building and dropping an elephant and a feather off a building in a vacuum?
If an elephant and a feather were dropped of a building the elephant would hit the ground before the feather because the feather would be acted on by air resistance. Thus causing it's fall to be slower. If they were both dropped in space, or in a vacuum, then they would both hit the ground.
You decrease the mass of a car, but want to keep the acceleration the same. The force of the car will ____.
Decrease
You are pushing a boulder that has the mass 10, 000 kg with a force of 100N and the boulder moves. Now your friend came along, He starts to push the boulder with you for an additional force of 100N. What is the acceleration on the boulder with your friends help when compared to you pushing the boulder yourself?
The acceleration will double when compared to the original acceleration
There is a boulder that has a mass of 50,000 kg and you pushed the boulder with 20N of force. The boulder is at rest after you apply the force. What is the acceleration when compared to the original acceleration?
Static friction
You are pushing a brick with 100N of force. Then your friends added 3 more bricks of equal mass and you are pushing these bricks with 100N. What is the acceleration when compared to the original acceleration?
The acceleration is 1/3 when compared to the original
What measurements are needed to calculate force?
Mass, Time, and Distance
_____ is when the acceleration is 0 and the object is still falling towards the earth.
Terminal velocity
When the force of gravity is the only force that act on an object and with little to no air resistance, then the object is in a state of ____.
Free fall
You have a mass of 50kg. Planet X has 1/2 times the gravity when compared to earth. What is a true statement that you can conclude from this information?
You will have a greater weight on earth.
On Earth Spongebob weighs 100 lbs, but Bob the cat weight's 100lbs on the moon. The moon has 0.16 times the gravity when compared to earth. What is a true statement that you can conclude from this information?
Bob the cat has the greater mass
The force of friction does not depend on speed. True or False?
True
The force of friction does depend on the area of contact. True or False?
False
If you decrease mass, you will also ____ inertia.
decrease
What are the 2 types of force that are important for acceleration and what would happen to the acceleration based on each force?
The two types of force that are important for acceleration are applied force and friction. Your applied force can either speed up or slow down your object. If you apply more force your acceleration will be faster. Friction because this can slow down or speed up your object because there is less friction then your object will go faster and if there is more friction then your object will slow down.
A 400kg bear grasping a vertical tree slides down at constant velocity. What is the friction force that acts on the bear?
Sliding Friction
Explain Friction and compare and contrast the different types of friction.
Friction is the force that counteracts applied force to slow down the object. Static friction is friction that keeps the object in place. It prevents the object from moving when there is no applied force. Sliding Friction is the friction when there are two objects sliding against each other and the more friction there is applied to harder it is to apply force to make fluid friction. This is the friction that makes it hard to move in water because the water molecules are close together applying more force.
What is the relationship between mass, weight and gravitational force?
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A rocket becomes progressively easier to accelerate as it travels through space. Why is this the case. (Note there are no gravitational force acting on the rocket, also 90% of the rockets mass is fuel when it was first launched.)
Because the rocket burned more fuel making the weight less and easier to accelerate. Also, gravity starts pulling the rocket down which helps it accelerate.
Why is a cleaver that has a mass of 2.27 more effective for chopping vegetable then a sharp knife that has a mass of 0.47 kg?
Because the cleaver has more weight which means it can apply more force when chopping the vegetable. Also you have to apply more force to cut which makes it a stronger cut.
Wherever there is an action force, there must be a reaction force, which ______.
is exactly equal in magnitude
If an archer shoots an arrow then the bowstring exerts an action force against the arrow. The reaction to this force is the _____.
arrow's push against the bowstring
If a rocket pushes on a gas then the rocket exerts an action against the gas. The reaction to this force is the _____.
gas pushes on the rocket
A baseball player bats a ball with a force of 2891 kg*m/s^2. The reaction force that the ball exerts against the bat is _____.
2819N
A Hummer and a Honda Civic traveling at the same speed have have a head-on collision. The vehicle that undergoes change in acceleration will be ____.
Honda Civic
A car traveling at 50km/hr strikes a bug and splatters it. The force of impact is _____.
the same for both
Mr. Snow Leopard hits a bag with 12lb. of force and the bag hits Mr. Snow Leopard with 21 lb. of force. True or False
False
Name an example of a scalar quantity.
Speed
You are pushing a brick with 40N of force. Then your friends add 3 more bricks of equal mass and you are pushing these bricks with 40N. What is the acceleration when compared to the original acceleration?
The acceleration is 1/4 when compared to the original
Cart A and Cart B are connected by a spring. Cart A and Cart B are pressed together on the spring and then the spring pushes on carts A and B. The force is ____.
the same for both
If Cart A has the mass of 100kg and Cart B has the mass of 10kg, which cart has the greater acceleration?
Cart B
The attraction of a person's body toward the Earth is called weight. The reaction to this force is: _______.
the person's body pulling on the Earth
Compare and Contrast vector quantity and scalar quantity. Give an example of each.
A vector quantity tells us the speed and direction of an object. An example of a vector quantity would be velocity. A scalar quantity only gives speed. An example of a scalar quantity would be speed.
You push a car by hand. The car in turn, pishes back with an opposite but equal force on you. Doesn't this mean that the forces cancel but one another making acceleration impossible?
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A baseball player hits a ball with a bat. Identify the action reaction pair when the ball is being hit.
action- bat hits ball
reaction- ball his bat
While the ball is in flight, identify the action reaction pair.
action- The ball goes through the air
reaction- gravity (air) pushes on the ball
Is it true that, when you drop from a branch to the ground below, the earth pulls on you and you pull on the earth. If so, then why is the acceleration of Earth not noticed?
Earth's acceleration is not noticed because due to it having so much Mass it's acceleration is extremely little compared to mine.
Mr. Snow Leopard his the wall with a 100N of force. Then Mr. Leopard hits a board with 60N of force. Both times he used the same amount of energy. Explain why there is a difference of force.
The wall is harder than the board. He has to push harder on the wall in hopes of getting the wall to move. He pushes with a smaller force on the board because the board is smaller than the wall.
Within a book at rest on a table, there are billions of forces pushing and pulling on all the molecules that make up the book. Why is it that these forces do not produce a net force that can cause the book to fly off the table? What is required to accelerate the book?
All the forces in the book cancel each other out. An external force is needed to accelerate the book.
Momentum is directly related to which of Newtons Laws of Motion?
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If you increase the force of an object, what will happen to velocity and momentum of the object?
Velocity will increase and momentum will increase
You maintain the change of momentum of an object, but decrease time. The force will _____.
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The net momentum right before collision will always be different from the net momentum right after a collision according to the law of conservation of momentum. True or False?
False
A Hummer and a Honda civic traveling at the same momentum and have a head-on collision. The vehicle that undergoes the greatest change in momentum is ____.
Honda Civic
Hummer and a Honda Civic each are traveling with a momentum of 100Ns. Honda civic has a small mass compared to the Hummer. What can you conclude with the given information?
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Why is it difficult for a fighter to hold a hose that ejects large amounts of water at high speed?
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A fully dressed person is at rest in the middle of a pond on a perfectly frictionless ice and must get to shore. How can this person make it to shore?
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Compare and contrast Elastic collision and Inelastic collision.
Elastic collision is when the collision does not cause damage to the objects and does not generate heat. Inelastic collisions cause damage to the objects and generate heat.
Explain momentum and discuss 3 ways to affect momentum.
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Discuss why a bouncing object generates more impulse than one that does not bounce.
A bouncing object generates more impulse because the impulse to throw an object and then for the object to bounce back combined is greater then the amount of impulse it takes to throw a non bouncing object.
What is the impulse when an average force is exerted on a cart for 2.5s?
50Ns
How much impulse stops a 50kg carton sliding at 4.5m/s when it meets a rough surface?
220kg*m/s
A cannon fires a cannon ball with a velocity of 10m/s. The mass of the cannon ball was 100kg. What is the net momentum of the Cannon-cannonball system?
1000Ns
A cannon fires a cannon ball with a velocity of 10m/s. The mass of the cannon ball was 100kg. What is the net momentum of the Cannon-cannonball system?
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Define Rotational Inertia.
The property of an object to resist change in a rotational motion.
Define Tangential Speed.
A measurement that measure distance traveled per unit of time in circular motion.
You apply 27N of force on a wrench...
As you decrease the radias where you apply the force, you will decrease the torque of the wrench.
Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by...
2
On a merry go round, Horse A has a radius from the center of 10m while horse B has a radius from the center of 15m. Which horse has a greater rotational speed?
Neither horse has a greater speed
Toss a baseball bat into the air and it wobbles about its ___.
center of mass.
When a twirling ice skater brings her arms inward, her rotational speed ___.
increases
As rotational speed of a merry go round double, what will happen to tangential speed?
increases 2 times
If you decrease the radius by half from the center of an axis, what will happen to centripetal force?
Increase 2 times
If you double velocity of a car that is turning, what will happen to centripetal force?
Increase 4 times
A torque acting on an object tends to produce ___.
rotation
On a balanced see saw, a cow is three times as heavy as his partner and the cow sits ___.
1/3 the distance from the fulcrum
The famous Leaning Tower of Prisa doesn't topple over because its center of gravity is ___
above a place of support
2 people are balanced on a see-saw. If one person leans toward the center of the see-saw, that person's end of the see-saw will ___.
rise
Define Centrifugal force.
The force directed away from a fixed center that causes an object to follow a circular path.
If a record player's rotational speed is doubled, then the tangential speed of a pet hamster sitting on the edge of the record will ___.
double
Compare ad contrast rotational speed and tangential speed.
Rotational speed is how many revolutions an object makes. Tangential speed is the distance an object covers while in a circular motion. If the rotational speed of an object increases then its tangential speed will as well.
Define rotational inertia and how it relates to angular momentum.
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What is the conservation of angular momentum and how does it relate to a figure skater spinning on the ice?
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What is the difference between Centripetal force and Centrifugal force?
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What is the relationship between Center of gravity and stability?
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Give an example of no work being done.
A package on the floor
If you increase the acceleration of an object, what would happen to the force and the work of an object?
Force would increase and Work would increase
You maintain the same amount of work when you pushed the car, but decrease time. The power wil ____.
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A person is holding a bottle of gasoline 5m above the ground. Based on this statement, name the correct types of potential energy.
Chemical and Gravitational potential energy
If time is increased, then power will ___.
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Potential energy is the energy of motion. True or False?
False
You increase the velocity 5 times, the kinetic energy will ___ assuming the mass is constant.
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Kinetic energy is an example of scalar quantity or vector quantity?
Scalar Quantity
A small ball and a similar large ball, at rest, are allowed to roll down an incline for only one second. At this instant the large ball will have a greater____.
potential energy, kinetic energy, and momentum
You and a Flight attendant toss a ball back and forth in a Boeing 747. Does the KE of the ball depend on the speed of the airplane?
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Why is it easier to stop a lightly loaded truck than a heavier one that has equal speed?
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Why does the force of gravity do work on a car that rolls down a hill, but no work when it rolls along a level part of the road?
Gravity pushes the ball toward the ground. So, when it is on a hill it moves down. This is work. When the ball is on a level road gravity does no work because the ball can not go downward on a level surface.
Explain why if you increase velocity of a car you will increase the power of the car.
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What is the metric system a multiple?
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How many meters are in 1.75 km?
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How many seconds are in 3 deka second?
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The dependent variable is a variable that is manipulated by the scientist. True or False?
False
What is the process of gathering information through the senses?
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Pennies made in 1982 are heavier than the pennies made in 2004 because of the different metal composition of pennies. This statement is an example of which step of the scientific method?
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What is plotted on the y-axes on a graph?
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What is a Hypothesis?
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What is the difference between a theory and a hypothesis?
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What is a histogram and why is it important?
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What is the scientific method and list the 5 steps.
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Give an example of the first 4 steps of the scientific method.
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During the pennies experiment, there were weight variations between the pennies. Give 3 reasons for the variation.
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A student was trying to discover the ratio between the Diameter of the coin and the distance from the index card. The student measured the diameter of the coin to be 2 centimeter. Then the student measured the distance between the coin and index card to be 220 centimeter. What is the ratio that the student discovered between the Diameter of the coin and the distance from the index card?
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The gravitational force acting on an object is ____.
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When a pair of equal but opposite forces acts on an object, the net force that results is ___.
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The property of matter that resists changes in motion is called ___.
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According to Aristotle, motion that was externally caused and imparted to objects because of pushes or pulls was a class of motion called ____.
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Copernicus reasoned that the simplest way to account for the observed motions of the Sun, Moon and plants was to assume that ___.
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Galileo found that a stone twice as heavy as another ___.
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Galileo recognized that friction was ___.
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In the absence of force, a moving object will continue moving was stated by:
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This person refined the idea that every object continues uniform motion in a straight line unless it is compelled to change that state by forces impressed upon it.
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This person is credited with the law of inertia that states an object has the tendency to stay at rest when there is no force acting on it.
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When the net force on something is zero, we say that something is in ___.
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The law of inertia applies to ___.
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Suppose there is a friction force of 10N acting on a box sitting on your desk. In order to move the box at a constant velocity, you would have to supply a force ____.
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If a 100-lb. person steps on a pair of bathroom scales and leans so that the reading on one scale is 60 lbs., the reading on the other scale is ____.
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A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This demonstrates that ___.
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The type of force counter gravity when you are standing on the floor is ___.
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The sum of all the forces acting on an object is called the ___.
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The force that opposes the motion of objects that touch as they move past each other is called ___.
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How did Galileo disprove 2 of Aristotle's theories?
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Compare and contrast Static and Dynamic equilibrium.
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Name 3 scientists that studied motion.
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