* Your friend has a pie on the roof of his van. You are standing on the ground and observe the van stopping abruptly for a red light. The pie does not slip off the roof. (a) Construct a motion diagram and a force diagram for the pie as the van approaches the red light, from your frame of reference and from the driver's frame of reference. (b) Repeat part (a) for the case when the light turns green. Be sure to specify the observer and identify the other object causing each force. (c) Are the motion diagrams consistent with the force diagrams for each case?
* Your friend has a pie on the roof of his van. You are standing on the ground and observe the van stopping abruptly for a red light. The pie does not slip off the roof. (a) Construct a motion diagram and a force diagram for the pie as the van approaches the red light, from your frame of reference and from the driver's frame of reference. (b) Repeat part (a) for the case when the light turns green. Be sure to specify the observer and identify the other object causing each force. (c) Are the motion diagrams consistent with the force diagrams for each case?
* Your friend has a pie on the roof of his van. You are standing on the ground and observe the van stopping abruptly for a red light. The pie does not slip off the roof. (a) Construct a motion diagram and a force diagram for the pie as the van approaches the red light, from your frame of reference and from the driver's frame of reference. (b) Repeat part (a) for the case when the light turns green. Be sure to specify the observer and identify the other object causing each force. (c) Are the motion diagrams consistent with the force diagrams for each case?
A 15.0 kg load of bricks hangs from one end of a rope that passes
over a small, frictionless pulley. A 28.0 kg counter weight is
attached to the other end of the rope, as shown in the figure. You
may model the rope as a massless string. The system is released
from rest.
A. Draw two freebody diagrams, one for the load of bricks and
one for the counter weight.
B. Find the magnitude of the upward acceleration of the load
of bricks.
28.0 kg
C. What is the tension in the rope?
D. How does the tension compare to the weight of the bricks
and the weight of the counter weight?
15.0 kg
An airplane flies at a constant speed in a horizontal straight path. Two
horizontal forces act on the plane: the thrust of the propeller and air
resistance. Which of the following statements can be correctly drawn from
the scenario above? *
The plane is being dragged by air, causing it to decelerate.
O Forces are acting on the plane, so it will accelerate.
O The net force acting on the plane is zero.
The thrust of the propeller is greater than the air resistance, causing the plane to
move forward.
A person places a cup of coffee on the roof of her car while she dashes back
into the house for a forgotten item. When she returns to the car, she hops in
and takes off with the coffee cup still on the roof. You may want to review
(Pages 156 - 163).
Part A
If the coefficient of static friction between the coffee cup and the roof of the car is 0.21, what is the maximum acceleration the car can have without causing the cup to slide? Ignore the effects of
air resistance.
Express your answer using two significant figures.
a =
m/s?
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• Part B
What is the smallest amount of time in which the person can accelerate the car from rest to 27 m/s and still keep the coffee cup on the roof?
Express your answer using two significant figures.
ΑΣφ.
t =
Submit
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