61 terms

# Physical Science Final Exam #2

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A passenger in the rear seat of a car moving at a steady speed us at rest relative to?
The front seat of the car
A person walks 1 mile every day for exercise, leaving her front porch at 9:00 am. and returning to her front porch at 9:25 am. What is the total displacement of her daily walk?
0
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 while maintaining the same displacement?
By driving west 6 blocks from the starting point
A ball is rolled uphill a distance of 5 meters before it slows, stops and begins to roll back. The ball rolls downhill 9 meters before coming to rest against a tree. What is the magnitude of the ball's displacement?
4 meters
Displacement vectors of 4 km south, 2 km north, 5 km south, and 5 km north combine to a total displacement of?
2 km south
Speed is the ratio of the distance an object moves to
the amount of the time needed to travel the distance
Instantaneous speed is measured
at a particular instant
The slope of a line on a distance-time graph is
speed
A horizontal line on a distance-time graph means the object is
at rest
vector addition is used when motion involves
more than one direction, velocity, and one speed
The rate at which velocity changes is called
acceleration
What identifies a change in motion that produces acceleration?
a ball moving at a constant speed around a circular track
Objects in free fall near the surface of the Earth experience
constant acceleration
What's an example the describes constant acceleration due ONLY to a change in direction?
traveling around a circular track
The slope of a speed-time graph indicates
acceleration
An object that is accelerating may be
Slowing down, changing direction, and gaining speed.
What is instantaneous acceleration?
How fast a velocity is changing at a specific instant
The motion of an object looks different to observes in different...?
Frame of references
The SI unit for measuring length is the?
meter
The direction and length of a straight line from the starting point to the ending point of an object's motion is?
Displacement
Displacement and velocity are examples of what? because they have both magnitude and direction.
vectors
The sum of two or more vectors is called the?
resultant vectors
speed is measured in units of?
m/s
A car's speedometer measures
instantaneous speed
v = d/t is the equation for?
speed
The difference between speed and velocity indicates the _____ of motion and speed does not
direction
two or more velocities add by
a moving object does not ______ if its velocity remains constant.
accelerate
Freely falling objects accelerate at 9.8 m/s2 because the force of _________ acts on them.
gravity
The velocity of an object moving in a straight line changes at a constant rate when the object is experiencing constant _____
acceleration
The acceleration of a moving object is calculated by dividing the change in _____ by the time over which the change occurs.
speed
Accelerated motion is represented by a _____ line o a distance-time graph.
curved
A car that increases its speed for 20 km/h to 100 km/h undergoes _____ acceleration.
positive
______ ______ is how fast a velocity is changing at a specific instant.
Instantaneous acceleration
Mass:
Is the amount of matter in an object, a measure of the inertia of an object, which depends on the amount of matter the object contains
Weight:
is the force of gravity acting o an object.
Inertia:
An object that is in motion stays in motion and an object at rest stays at rest as long as the net forces acting on that object are zero
Newton's 1st Law states:
The law of Inertia
SI unit for force
Newtons (N)
Weight formula:
w=m.g
1 N:
kg x m/s(2)
N/kg
m/s(2)
Force
Push or pull on an object
Vector
Magnitude and direction
List 4 things that are vectors
Velocity, Acceleration, Force, and Gravity
Force (SI unit):
Newton
Acceleration (SI unit):
m/s(2)
Velocity (SI unit):
1 m/s(2)
Formula for Newton:
km x 1 m/s(2)
What is a net force?
forces combined when they are acting on an object (they can be pushed or pulled)
What do we call it when net forces are zero acting on an object (so there is no change in the object's motion)?
balanced force
True/False: All moving objects are subject to friction.
True
Formula for Newton's 2nd Law of Motion
acceleration= net force / mass or a=f/m
Formula for Momentum
mass x velocity
SI Unit for Momentum
kg x m/s
Newton's Third Law of Motion
For every action there is an equal and opposite reaction.
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.
(True or False) Force always exist in pairs.
True
(True or False) Only when equal and opposite forces act on the same object do they result in a net force of zero.
True
(True or False) Momentum is a vector
True
Law of Conservation
If no net force acts on a system, then the total momentum does not change.
What is conserved when 2 objects collide in a closed system?
Momentum