Download Unit 2 Study Guide Answer Key

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Unit 2 Study Guide
1. What is a reference point?
A reference point is a place or object used for comparison to
determine if something is in motion.
2. What are some examples of
descriptions of direction?
Up, down, left, right, east, west, north, south
3. What is the difference between
speed and velocity?
Speed is a measure of distance over time. Velocity is distance
over time in a certain direction.
4. How is average speed calculated?
Average speed is total distance divided by total time.
5. How is acceleration calculated?
Acceleration is a change in speed over time:
𝑓𝑖𝑛𝑎𝑙 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 − 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦
𝑡𝑖𝑚𝑒
Acceleration always involves two measurements of time
because it is a measure of a change in velocity (distance over
time) over time.
A horizontal line on a distance or position over time graph
means that the object is at rest (stopped).
6. Why does acceleration always
involve two measurements of time?
7. What does a horizontal line on a
distance or position over time graph
mean?
8. What does a horizontal line on a
velocity or speed over time graph
mean?
9. What is a force?
A horizontal line on a velocity or speed over time graph means
that the object is moving at a certain speed.
A force is a push or a pull.
10. What is the relationship between
force and acceleration?
The more force put on an object, the more it will accelerate.
The object will move in the same direction.
11. How do you find the net force on
an object if two forces are acting in
the same direction?
12. How do you find the net force on
an object if two forces are acting in
opposite directions?
If two or more forces are acting on an object in the same
direction, you find the net force by adding the forces together.
If two or more forces are acting on an object in opposite
directions, you find the net force by subtracting the forces.
The object will move in the direction of the greater force.
13. Describe the motion of a skydiver The skydiver will be moving at a constant velocity when he
who reaches terminal velocity. (page reaches terminal velocity. This happens when the force of air
152)
resistance is equal in magnitude and opposite in direction to
the force of gravity.
14. What force is demonstrated by
the tablecloth trick?
Inertia is demonstrated by the magician’s tablecloth trick. The
objects’ inertia causes them to stay on the table when the
cloth is quickly removed.
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15. What is inertia?
Inertia is the resistance to a change in motion.
16. What is the relationship between
mass and inertia?
17. What is gravity?
The more mass an object has, the more inertia it will have.
18. What two factors influence
gravity?
The strength of the gravitational force between two objects
depends on two factors, mass and distance.
19. Why would you be able to jump
higher on the moon than on Earth?
You would be able to jump higher on the moon than Earth
because the moon’s mass is much less than that of Earth, thus
the moon exerts less gravitational pull on a body.
20. What is friction?
Friction is a force that opposes motion between two surfaces
that are in contact with each other.
21. What are two ways to increase
friction?
Friction can be increased by increasing pressure or by creating
a rougher or more adhesive surface.
22. What force is air resistance a
type of?
Air resistance is a type of friction.
Gravity is a force of attraction between objects due to their
masses.
23. Name and describe the six simple
machines.
a. wedge
two inclined planes placed back-to-back and used to split or lift
objects
b. wheel and axle
a wheel with a rod running through the wheel
c. pulley
a grooved wheel with a chain or rope wrapped in the groove
d. inclined plane
a flat slanted surface that makes it easier to move an object up
a distance
e. lever
a bar that turns on a point
f. screw
an inclined plane wound around a cylinder or a cone
24. When referring to a simple
machine, what is the load?
The load is a force or object which must be overcome by
the machine.
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25. What is a fulcrum?
The point on which a lever pivots is called a fulcrum.
26. What is mechanical advantage?
Mechanical advantage is the number of times a machine
increases the input force.
27. What is mechanical efficiency?
Mechanical efficiency is the ratio of output work to input
work. The formula is work output/work input x 100 and is
given as a percentage.
28. What is the work done on a
machine?
The work done on a machine is called work input.
29. What is the work done by a
machine?
The work done by a machine is called work output.
30. What is the purpose of a
machine?
The purpose of a machine is to make work easier.
31. How can you increase the
mechanical advantage of an inclined
plane?
32. How can you increase the
mechanical advantage of a lever?
You can increase the mechanical advantage of an inclined
plane by increasing the length of the ramp.
You can increase the mechanical advantage of a lever by
moving the fulcrum closer to the load.
34. Calculate the overall average
speed.
10 m / 6 sec = 1.67 meters per
second
Distance (m)
33. Label the diagram: (1) most
potential energy (2) least potential
energy (3) most kinetic energy (4)
least kinetic energy
15
10
5
0
0
2
4
Time (sec)
6
35. Calculate the speed of the object
for each leg of the journey.
0 – 2 = 1 meter per second
2 – 4 = 2 meters per second
Distance (m)
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15
10
5
0
0
4 – 6 = 1 meter per second
2
4
6
Time (sec)
Distance (Km)
36. Write a story to match the graph.
140
120
100
80
60
40
20
0
12
0 – 2 = .25 m/s/s
2 – 4 = .5 m/s/s
14
15
Time (hr)
16
17
6
Speed (m/s)
37. What is the acceleration of the
object for each leg of the graph?
13
4
2
0
4 – 6 = 1.75 m/s/s
0
2
4
6
Time (sec)
38. Describe the difference between
a speed and acceleration graph.
Speed is distance divided by time. Acceleration is speed
divided by time. Acceleration represents a change in speed,
direction or both.
39. State Newton’s 1st Law of Motion
and give a real example.
An object at rest will stay at rest, and an object in motion will
continue in motion in a straight line unless acted on by an
outside force.
40. State Newton’s 2nd Law of
Motion and give a real example.
The tablecloth trick is an example.
Force is equal to mass times acceleration.
It’s harder for a big truck to stop than it is for a small car.
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41. State Newton’s 3rd Law of
Motion and give a real example.
42. Calculate:
Net force______12N_____________
Direction of movement right
43. Calculate:
Net force___3N
Direction of movement__ right
For every action, there is an equal and opposite reaction.
Rockets being shot into space. The exhaust pushing out
produces an equal and opposite for pushing back up.