Transcript Review PPT

Newton’s Laws Concept
Questions
Clicker Questions/WS Key
It is possible to have motion in the absence of a
force.
A.
B.
True
False

What is the tension in the cable of an elevator with a
weight of 8800 N that ascends with an acceleration of
1.30 m/s2?



Draw the free body diagram
Sum the forces in the y direction
Solve for tension
2. If an object isn’t moving, no external force acts on it.
A.
B.
True
False
3. If a single force acts on an object, the object
accelerates.
A.
B.
True
False
4. If an object is accelerating, a force is acting on it.
A.
B.
True
False
 A 500.



N stoplight just turned red.
What is the mass of the stoplight?
What is the weight of the stoplight?
What is the force of gravity on the stoplight?
5. If an object isn’t accelerating, no external force
is acting on it.
A.
B.
True
False
 Calculate
the acceleration of the system &
the tension in the rope.
100.
175.
kg
kg
6. If the net force acting on an object is in the
positive x-direction, the object moves only in the
positive x-direction.
A.
B.
True
False
7a. A small sports car collides head on with a
massive truck. Which vehicle will experience the
greatest magnitude force?
A.
B.
C.
The car.
The truck.
Neither, it is the same
7b. A small sports car collides head on with a
massive truck. Which will undergo the greater
magnitude acceleration?
A.
B.
C.
The car.
The truck.
Neither, it is the same.
8a. When throwing a baseball, a force is exerted
by the hand on the ball. Is this force a field force or
a contact force?
A.
B.
Field Force
Contact Force
8b. Throwing a ball 6 m straight upwards requires
a 25 N throwing force. How strong is the throwing
force it experiences when the ball is half way to the
top?
A.
B.
C.
D.
More than 25 N
Less than 25 N (but more than 0 N)
Exactly 25 N
0N
 A full
moving box has a mass of 20.0 kg. If
a net force of 30. N is applied to it, what is
its acceleration?
9. A space explorer is moving through space far
from any planet or star. He notices a large rock,
taken as a specimen from an alien planet, floating
around the cabin. Should he push is gently or kick
it toward the storage compartment? Why?
A.
B.
Push it gently.
Kick it.
10. Identify the action reaction pairs
in the following situations:
 Snowball
hits a girl in the back.
 A baseball player catches a ball.
 A man takes a step.
 A gust of wind strikes a window.
11. A truck loaded with sand accelerates along a highway. If
the driving force stays the same on the truck, what
happens to the truck’s acceleration if its trailer leaks sand
at a constant rate through a hole in the bottom?
A.
B.
C.
Acceleration increases.
Acceleration decreases.
Acceleration stays the same.
 Calculate
the magnitude (number, not
direction) of the resultant vector:
X
20. N
40. N
25o
15 N
Y
12. A passenger sitting in the rear of a bus claims that she
was injured as the driver slammed on the breaks, causing a
suitcase to come flying towards he from the front of the
bus. If you were a judge in this case, how would you rule
and why?
A.
B.
Judge should rule in the lady’s favor
because she is telling the truth.
Judge should rule against the lady
because she is lying.
13. Tiger Woods can hit a golf ball with 55 N of force. How
hard does the ball hit back on the club?
A.
B.
C.
More than 55 N of force
Less than 55 N of force
Exactly 55 N of force


Two forces act on an object on a frictionless surface.
Rank each situation from greatest to least change in
velocity (note all vectors directed to the right are positive,
and those to the left are negative. Also 0 m/s > -10 m/s
14. What action reaction pair is responsible for
pushing a car forward?
15. A rubber ball is dropped to the floor. What force causes
the ball to bounce? Does the Earth “bounce” too?
A.
B.
Yes
No
16. While rummaging in her backpack for her cell phone,
Sally’s Mini-Cooper rear ends Joey’s Suburban. Sally’s car
is totaled while the suburban is fine. If Sally’s car hit the
suburban with 30 N of force, how much force did Joey’s car
exert on Sally’s?
A.
B.
C.
More than 30 N of force
Less than 30 N of force
Exactly 30 N of force
17. Helpful Henry’s car is pushing Flat-tire Fred’s car to the
car shop. While the cars are accelerating up to 15
miles/hour Helpful Henry needs to push Fred’s car with 60
N of force. With what force does Flat-tire Fred’s car push
on Helpful Henry’s car?
A.
B.
C.
More than 60 N of force
Less than 60 N of force
Exactly 60 N of force
18. An army plane wants to drop supplies to a group of
physics students stranded on an island. In order for the
package to land on the island, the pilot needs to drop the
package before the plane is directly above the island.
Explain why using Newton’s Laws (you may ignore air
resistance).
A.
B.
C.
Newton’s 1st law explains this.
Newton’s 2nd law explains this.
Newton’s 3rd law explains this.
is standing on a 10.0o hill.
Calculate the coefficient of friction
between the person’s shoes and the hill
so that the person stays standing in
place instead of sliding down the hill.
 Is this the coefficient of static friction or
of kinetic friction?
 A person