Download Forces and Motion Review Sheeteoct answers

Forces and Motion Review Sheet- EOCT Physical Science
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What are the 4 differences in weight and mass?
Weight is gravitational pull, mass is the amount of matter in an object; weight is measured in Newtons, mass is measured in
kg; weight is measured on a spring scale, mass is measured on a triple beam balance; weight depends on location in the
universe, mass is constant.
What is the difference in speed and velocity?
Speed is the distance in a specific amount of time. Velocity is speed with a direction.
Calculate the speed of an object that traveled 50 miles in 25 seconds. (formula, work with units and answer with units.)
S=d/t= 50mi/25s= 2 mi/s
Calculate the distance an object travels if it is traveling at 55 miles per hour in .25 hours. (formula, work with units and
answer with units.)
D=sxt= 55mi/hr*.25hr= 13.75 miles
What is the acceleration of an object that slows to 0m/s after traveling 55m/s in 15s.
A= fv-iv/t= 0m/s-55m/s/15s= -3.67m/s2
Negative acceleration tells you what? Positive acceleration tells you what?
Negative is slowing down…positive is speeding up
What are the 3 ways you can accelerate?
Speed up, slow down, change directions
8. This is the graph of a journey by sports car:
What would the speed of the sports car be at 14:00? (2:00 pm)
S=d/t= 100km/3hr= 33.33 km/hr
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At what point(s) is speed constant? A-b, e-f
At what point(s) is there no movement? C-d
At what point(s) is there positive acceleration?o-a, d-e
At what point(s) is there negative acceleration?a-c
10. What does this graph show?
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Constant speed
Constant acceleration
No movement
Changing acceleration
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a. Constant speed
b. Constant acceleration
c. No movement
12. At what point is the car stopped?
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AT point B it is stopped (same distance)
A block is placed on a horizontal table. The block is then pulled to the right with a string. The block remains at rest. A
spring scale, attached to the string, reads 7.5 N. Which force acting on the block is equal to 7.5 N?
a. gravitational force exerted on block
b. force to the left exerted by air
c. upward force exerted by table
d. force exerted by static friction
On the moon, gravity causes a rock hammer to fall more slowly to the ground than on Earth. Which lunar factor directly
causes the slower rate of fall?
a. smaller radius
b. slower rotation
c. lower density
d. lesser mass
A 300-N force acts on a 25-kg object. What is the acceleration of the object? A = f/m= 300N/25kg= 12m/s2
The mass of an object is 255kg and the acceleration is 25m/s2. What was the force applied? F= ma= 255kg x 25m/s2= 6375N
The size of the gravitational force between two objects depends on their…
a. frictional forces
b. inertia
c. masses and the distance between them
d. speed and direction
18. A penny is dropped from the top of a building. Neglecting air resistance, about how fast is it going after 4 sec? 4s x
9.8m/s2= 39.2m/s
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What was the bus’ acceleration during the time from B to C?
A=fv-iv/t= 0m/s-10m/s/3s= -3.33m/s2
20. You are a linebacker for UGA and weight 260 pounds (118kg). What would your weight be on the moon? What would
your mass be on the moon? Weight/6= 260pounds/6= 43.33pounds…mass is 118kg…ALWAYS stays the same!
21. The person in the car does not have on a seatbelt. Why does the person fly out of the car when it hits the wall?
Inertia…your body wants to continue in a straight line forward
22. What causes acceleration, balanced or unbalanced forces?UNBALANCED FORCES!!
23. What is Newton’s 1st Law? An object in motion stays in motion….an object at rest remains at rest, unless acted upon by an
external force.
24. What is Newton’s 1st Law also called? INERTIA
25. What is Newton’s 2nd Law? Force= mass x acceleration
26. What is Newton’s 3rd Law? For every action, there is an equal and opposite reaction
27. Which would have more inertia, a rock or a boulder and why? Boulder- more mass= more inertia
28. If you have a transfer truck and a small car, which would require the most force to put them at the exact same
acceleration? Transfer truck b/c it has more mass
29. If you have 2 marbles of equal mass that are accelerating at the exact same rate, what does this tell you about the force
applied to them? They had the exact same force applied.
30. A gun is fired. What is the action? Reaction? Action- gun firing forward…reaction- recoil (kickback) of gun
31. A swimmer swims. What is the action? Reaction? Action= push arms backward Reaction- body goes forward
32. You sit in your chair. What is the action? Reaction? Action- you push down on the chair- reaction- chair pushes back up on
you…hopefully ;-)
33. A balloon is let go. What is the action? Reaction? Action- air comes out bottom Reaction- balloon flies in opposite
direction
34. A rocket goes up. What is the action & reaction? Action- water and air comes out the bottom…Reaction- rocket goes up
35. What is inertia? The tendency of an object to resist change in its current motion.
36. What is friction? The opposition to movement between two surfaces
37. What are the 3 types of friction? Sliding, rolling, static
38. Which type of friction takes the most force to overcome? Static
39. If you drop a paper and a book, which would hit first and why? Book b/c paper has more air resistance
40. If you are on the moon, how would #39 change? Both would hit at the same time b/c the moon has no air resistance
41. What is terminal velocity and how is this achieved? Terminal velocity is the rate of speed where a falling object can no
longer go faster. This happens because the air resistance pushing upward is equal to the gravity pushing downward
42. An object has a mass of 25kg. What is its weight?
Weight= 25kg x 9.8 m/s2= 245N
43. What is a projectile and how does this travel? A projectile is a thrown object and it always travels back to the Earth in a
curved path.
44. If you throw a ball and drop another, which hits first? Both hit at the same time!
45. What is centripetal force and what causes this? Centripetal acceleration is acceleration toward the center of a curved path.
Centrifugal 'force' is really a function of the inertia of the object being pushed into a circle. It is not really a force at all, it is
simply the tendency of an object to go in a straight line.