123 terms

# Lentz Final Exam

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By driving west 6 blocks from the starting point
A person drives north 6 blocks, then turns west, and drives 6 blocks. The driver then turns south and drives 6 blocks. How could the driver have made the distance shorter wile maintaining the same displacement?
velocity
The slope of a line on a displacement time graph is what?
at rest
A horizontal line on a displacement-time graph means the object is what?
4 m/s
What is the velocity of a bobsled whose displacement-time graph indicates that it traveled 100m in 25s?
10 m/s
A displacement-time graph indicates that an object moves 100m in 4s and then remains at rest for 6s. Whats is the average velocity of the object?
acceleration
The rate at which velocity changes is called?
a ball moving at a constant speed around a circular track
Which example identifies a change in motion that produces acceleration?
-6m/s^2
An object moving at 30 m/s takes 5s to come to a stop. What is the object's acceleration?
acceleration
The slope of a velocity time graph indicates?
linear, sloping downward
A velocity-time graph shows that a car moves at 10 m/s for 10 s. The car's speed then steadily decreases until it comes to a stop at 30 s. Which of the following describes the slope of the speed-time graph from 10 s to 30 s?
Sloping down, sloping up, changing direction
An object that is accelerating may be?
True
An object at rest has an instantaneous acceleration of zero.

True or False?
the object accelerates
When an unbalanced force acts on an object..?
equal to zero
When a pair of balanced forces acts on an object, the net force that results is..?
gravity and air resistance
The forces acting on a falling leaf are what?
The downward force of gravity and an initial forward velocity
Projectile motion is caused by..?
inertia
The property of matter that resists changes in motion is called?
the orange's inertia
An orange might roll off your cafeteria tray when you stop suddenly because of what?
6m/s^2
If a force of 12 N is applied to an object with a mass of 2 kg, the object will accelerate at...?
when a tennis rackets strikes a tennis ball, when stepping from a curb, when rowing a boat
In which of the following are action and reaction forces involved?
momentum
The product of an object's mass and velocity is its what?
momentum
What is conserved when two objects collide in a closed system?
250kg.m/s
What is the momentum of a 50-kilogram ice skater gliding across the ice at a speed of 5 m/s?
increases or distant decreases
The gravitational force between two objects increases as mass..?
centripetal force
The force that keeps an object moving in a circle is called?
Acts as an unbalanced force on the satellite, and changes the direction of the satellite
The centripetal force acting on a satellite in orbit..?
kinetic energy
The energy of motion is called?
40 J
A small 20-kilogram canoe is floating downriver at a speed of 2 m/s. What is the canoe's kinetic energy?
4.2 m/s
A 13-kg sled is moving at a speed of 3.0 m/s. At which of the following speeds will the sled have twice as much kinetic energy?
its speed
An object's gravitational potential energy is NOT directly related to which of the following?
The objects acceleration due to gravity is less on the moon
Why is the gravitational potential energy of an object 1 meter above the moon's surface less than its potential energy 1 meter above Earth's surface?
118 J
A 4-kilogram cat is resting on top of a bookshelf that is 3 meters high. What is the cat's gravitational potential energy relative to the floor if the acceleration due to gravity is 9.8 m/s2?
Reference level from which the height is measured
The gravitational potential energy of an object is always measured relative to the..?
chemical energy
The energy stored in gasoline is..?
False
Energy can be created or destroyed and energy can be transformed from one form to another.

True or False
kinetic energy plus its potential energy
The mechanical energy of an object equals its..?
chemical to thermal to mechanical
Which of the following describes the energy transformations in a car's engine?
work is done in climbing stairs, lifting a book and pushing a shopping cart..so none of the above.
In which of the following is no work done?
A and C (first and middle)
The kinetic energy of the pendulum bob in Figure 15-1 increases the most between locations..?
the force is not in the direction of the object's motion
A force acting on an object does no work if..?
joule
What is the unit of work?
9.0 J
If you exert a force of 10.0 N to lift a box a distance of 0.9 m, how much work do you do?
4.0 m
If you perform 40 joules of work lifting a 10-N box from the floor to a shelf, how high is the shelf?
watt
SI unit of power?
its rate of doing work
The power of a machine measures what?
700 W
If you exert a force of 700 N to walk 6 m up a flight of stairs in 6 s, how much power do you use?
True
To increase power, you can increase the amount of work you do in a given amount of time, or you can do a given amount of work in less time.

True or False?
force
A machine is a device that can multiply what?
increase a force and increase the distance a force moves an object
When a machine does work, it cannot do which of the following?
by changing the direction of your force
How can a machine make work easier for you?
No
Can you make the work output of a machine greater than the work input?
less than the ideal mechanical advantage of the machine
The actual mechanical advantage of a machine is?
If you know the input distance and output distance of a machine, which of the following can you calculate?
3
A 120-m long ski lift carries skiers from a station at the foot of a slope to a second station 40 m above. What is the IMA of the lift?
10
If you have to apply 40 N of force on a crowbar to lift a rock that weights 400 N, what is the actual mechanical advantage of the crowbar?
increase its efficiency
Reducing friction in a machine..?
some work input is lost to friction
The efficiency of a machine is always less than 100 percent because..?
55%
A mechanical device requires 420 J of work to do 230 J of work in lifting a crate. What is the efficiency of the device?
320 J
A motor with an efficiency of 75 percent must supply 240 J of useful work. What amount of work must be supplied to the motor?
increasing the distance through which the force is applied
An inclined plane reduces the effort force by..?
wedge
An ax is an example of a(an)
an automobile steering wheel
Which of the following is an example of a wheel and axle?
number of rope segments supporting the load
The ideal mechanical advantage of a pulley system is equal to the
dividing the radius of the wheel by the radius of the axle
The ideal mechanical advantage of a wheel and axle is found by
bicycle
An example of a compound machine is a..?
is made up of town or more simple machines that operate together
A machine is classified as a compound machine if it
Celsius degree
Which of the following is a unit of temperature?
temperature
Heat is the transfer of thermal energy from one object to another because of a difference in
temperature
What property of an object is related to the average kinetic energy of the particles in that object?
thermal energy of the object
As the temperature of an object rises, so does the
thermometer
Which of the following devices is based on the property of thermal expansion?
Mass, Phase, Temperature
Thermal energy depends on an object's
C
In the formula , which quantity represents the specific heat?
C(Specific Heat)
In the formula , which quantity is measured in units of J/g·°C?
Q=0.75g' 0.385J/gC' 22C
The specific heat of copper is 0.385 J/g·°C. Which equation would you use to calculate the amount of heat needed to raise the temperature of 0.75 g of copper from 7°C to 29°C?
Change in temperature
What does a calorimeter directly measure?
Energy from the sun reaches Earth mostly by
conduction and convection
Matter is needed to transfer thermal energy by
Convection and Conduction
The vacuum inside the thermos bottle shown in Figure 16-1 stops which type of thermal energy transfer to keep the liquid hot?
metal
Which of the following materials conducts heat well?
displacement
The direction and length of a straight line from the starting point to the ending point of an object's motion is _______________.
m/s
Velocity is measured in units of __________.
constant
A constant slope on a displacement-time graph indicates __________speed.
direction
The difference between speed and velocity is that velocity indicates the ___________ of motion and speed does not.
5
A displacement-time graph indicates an object moves 20 km in 4 h. The average velocity of the object is ________ km/h.
direction
Because its _________ is always changing, an object moving in a circular path experiences a continuous change in velocity.
accelerate
A moving object does not _________ if its velocity remains constant.
gravity
Freely falling objects accelerate at 9.8 m/s2 because the force of _________ acts on them.
acceleration
The velocity of an object moving in a straight line changes at a constant rate when the object is experiencing constant _______.
No
Can the size of an object's displacement ever be greater than the distance the object travels?
Yes
Can the size of an object's displacement ever be less than the distance the object travels?
No
If the speedometer on a car indicates a constant speed, can you be sure the car is not accelerating?
curved
Accelerated motion is represented by a(n) _________ line on a distance-time graph.
positive
A car that increases its speed from 20 km/h to 100 km/h undergoes _________acceleration.
force
A push or pull is an example of a(an) ___________
friction
The force that opposes the motion of objects that touch as they move past each other is called _________.
greater
It usually takes more force to start an object sliding than it does to keep an object sliding because static friction is usually __________ than sliding friction.
air resistance
The two forces acting on a falling object are gravity and _________.
0
When a falling object reaches terminal velocity, the net force acting on it is _________
projectile
The path of motion of a thrown javelin is an example of _____________ motion.
inertia
The tendency of an object to resist any change in its motion is called _______________
inertia, forward
During a head-on auto collision, ___________ causes a passenger in the front seat to continue moving _______.
force, mass
The acceleration of an object is equal to the net ________ acting on the object divided by the object's ________.
height
The force of gravity acting on an object is the object's ____________
bowling
If a golf ball and bowling ball are rolling at the same speed, the ______ ball has greater momentum
wall
When you push on a wall, the _____ pushes back on you.
equals
In a closed system, the loss of momentum of one object _______ the gain in momentum of another object.
mass
If the ______ of an object doubles, its kinetic energy doubles.
potential
Energy that is stored due to position or shape is called ______ energy.
mechanical
The sum of the kinetic energy and potential energy of an object is called its _________energy.
conservation of energy
"Energy cannot be created or destroyed" is a statement of the law of ______________.
0 J
When an apple falls from a tree to the ground, the apple's beginning kinetic energy and ending gravitational potential energy are both equal to __________.
C
In Figure 15-1, the kinetic energy of the pendulum bob is largest at location ____________.
A & E
In Figure 15-1, the gravitational potential energy of the pendulum bob is largest at locations ______.
Scaler
Time

Vector or Scaler?
Scaler
Distance

Vector or Scaler?
Vector
Displacement

Vector or Scaler?
Scaler
Speed

Vector or Scaler?
Vector
Velocity

Vector or Scaler?
Vector
Acceleration

Vector or Scaler?
Vector
Force

Vector or Scaler?
Vector
Momentum

Vector or Scaler?
hey, it's bailey. i decided 2 add a extra card. so wuts^. im trying to sudy and it's not working.
FML.