Download Ch. 12 Review Period: Name: Physical Science Date: Remember as

Ch. 12 Review
Physical Science
Period:
Name:
Date:
Remember as you answer these ASK YOURSELF WHY IT WORKS AND WHAT THAT MEANS.
If you UNDERSTAND and can apply all these concepts, you’ll do well, if you just memorize all the
answers and can’t apply the knowledge to other situations, you won’t do well.
1. A force is a
on one object by another object.
2. The SI unit of force is the
3. What are the base metric units of the unit from #2?
4. When an unbalanced force acts on an object (when there is a net force), what happens to the
object?
5. When an object has no net force acting on it, what happens to the object?
6. What kind of friction occurs: as a fish swims through water?
; as a book is
slid across a tabletop?
; and as a cabinet is pushed but doesn’t move?
7. Which is bigger, starting friction or sliding friction?
8. How does surface area affect sliding friction?
9. As you push a cereal box at constant velocity across a tabletop, the sliding friction acting on the
cereal box is in the
direction of the motion, and the magnitude of the
sliding friction is
the magnitude of the pushing force.
10. The property of matter that resists changes in motion is called
11. Two parachutists, Bob and Murray, jump out of an airplane at the same time. Murray has a mass
of 80kg, while Bob has a mass of 40kg, who will hit the ground first?
12. The two aspects that affect terminal velocity are
and
13. What happens when an object reaches terminal velocity while in falling through an atmosphere in
terms of forces and accelerations:
14. If a 1kg object has a terminal velocity of 10m/s, what would the terminal velocity of a 4kg object
if it was the same size and shape? Show your work!
15. A 20kg object has a terminal velocity of 50m/s, if another object of the same size and shape has a
terminal velocity of 100m/s, what is the new object’s mass? Show your work!
16. A 1000 kg car accelerates at 2 m/s2, what is the net force on the car?
17. According to Newton’s second law of motion, the acceleration of an object equals the net force
acting on the object divided by the object’s
18. The formula for finding your weight is:
19. Newton’s third law of motion describes what forces?
20. What type of forces have reaction forces?
21. What really dictates who will win a game of tug-of-war (don’t say whoever pulls harder)?
22. The product of an object’s mass and velocity is its
and
is defined as
23. What is the momentum of a 50-kg ice skater gliding across the ice at a speed of 2 m/s?
24. When you jump in the air, how does the force the earth pulls on you compare to the force you pull
on the earth?
25. Two of the same type of cannons fire two cannonballs of the same size at the same launch
velocity. One cannonball is solid steel, while the other cannonball is also steel but hollow in the
middle. Which will have the greater momentum?
26. How do the direction of net force compare to the direction of acceleration?
27. What happens when the net force points in the same direction as the object’s velocity?
28. What happens when the net force points in the opposite direction as the object’s velocity?
29. What happens when the net force points 90˚ to the object’s velocity?
30. What are the 4 universal forces:
31.
32.
33.
34.
35.
36.
Which of the universal forces is the weakest?
Which of the universal forces is the strongest?
Which of the universal forces is most effective over long distances?
Which of the universal forces acts over the shortest distance?
Which universal forces can both attract and repel?
What evidence do we have that nuclear forces are much stronger than electromagnetic forces at
very small distances?
37. Draw and label (BOTH value and name) the force diagrams for each of the following scenarios:
a. A 5N block on a flat surface being pushed
b. A 500N person standing motionless on a flat
with 10N of force to the left at constant
surface pushing with a 100N force to the
velocity (hint, what does constant velocity
right against a wall. (hint: you’ll have to use
mean).
Newton’s 3rd Law)
38. Complete the following force diagrams by writing in the missing names, values, or both (arrows
not to scale):
a. A 20N object is being pushed and is sliding
b. A 10N object is being pushed along a flat
to the right on a table against 40N of
table and is increasing speed to the right,
friction, with a net force of 30N to the left.
there is a 20N net force, and 20N of friction.
Ftable:
FEarth:
N
Ftable:
N
Is the object increasing speed, decreasing
speed, changing direction or a
combination?
FEarth:
N
N
Is the object increasing speed, decreasing
speed, changing direction or a
combination?
39. A person argues that when you jump in the air, you cannot be pulling the earth with the same force
as it pulls you because the earth is not drawn towards you. What is wrong with this argument?
Make sure you use a = Fnet/m in your answer.
40. A 5kg gun, suspended in the air by strings, fires a 0.01kg bullet (initially at rest). The bullet
leaves the barrel with a velocity of 200m/s after 0.001s. Assume constant acceleration while in
the barrel:
a. How much net force was applied to the bullet? (Hint, find acceleration first) Show your work!
b. How much acceleration would the gun recoil with? (hint: use Newton’s 3rd law first then the
Newton’s 2nd Law). Show your work!
41. A 15kg cannonball is fired perfectly horizontal from a 500kg cannon on wheels (assume no
friction). The cannonball leaves the cannon with a speed of 300m/s.
a. What is the momentum of the cannonball after firing, and what must the momentum of the
cannon be after firing the cannonball?
b. Assuming momentum is conserved, what will the cannon’s recoil velocity be after firing the
cannonball?
42. 70kg Gertrude and her 30kg granddaughter Sally are ice skating. Gertrude is initially going 5m/s
to the right while Sally is going 2m/s to the left. Gertrude runs into and picks up Sally. What will
their combined velocity be the instant after the collision?
43. A 20kg object is on a flat surface pushed to the right with 100N, there is 20N of sliding friction.
Draw the force diagram for this situation, then find the net force on the block, and then the block’s
acceleration.
44. A 40kg object is being pushed such that it accelerates at 2m/s2 along the flat floor with 20N of
friction. Complete the force diagram for this situation. (Note that arrows may not be to scale)
Ffloor:
Fsurface: 20N
N
Fperson:
FEarth:
N
N
45. A large German Shepard pulls on the leash of a small Chihuahua, and the Chihuahua strains to get
away. Which dog pulls harder on the leash? How do you know?