Practice Final Exam 2
Physics 11
Problem 1
The longest recorded pass in an NFL game traveled 83 yards in the air from the quarterback to
the receiver.
a. For the ball’s entire motion, (i) draw a motion diagram and (ii) plot y, vy vs. t.
b. Assuming that the pass was thrown at the optimal 45° angle, what was the speed at which
the ball left the quarterback's hand? Hint: cannot use the range equation to solve this.
Problem 2
A 1000 kg car pushes a 2000 kg truck that has a dead battery. When the driver steps on the
accelerator, the drive wheels of the car push backward against the ground with a force of 4500 N.
a. What is the magnitude of the force of the car on the truck?
b. What is the acceleration of the truck?
Problem 3
Two 500 g blocks of wood are 2.0 m apart on a frictionless table. A 10-g bullet is fired at 400
m/s toward the blocks. It passes all the way through the first block, then embeds itself in the
second block. The speed of the first block immediately afterward is 6.0 m/s.
a. What is the speed of the second block after the bullet stops?
b. Draw an impulse-momentum bar diagram for the situation.
Problem 4
A cannon tilted up at a 30° angle fires a cannon ball at 80 m/s from atop a 10-m-high fortress
wall.
a. What is the ball's impact speed on the ground below?
b. Draw a picture of the situation and an energy bar diagram
Problem 5
Glycerin is poured into an open U-shaped tube until the height in both sides is 20 cm. Ethyl
alcohol is then poured into one arm until the height of the alcohol column is 20 cm. The two
liquids do not mix. What is the difference in height between the top surface of the glycerin and
the top surface of the alcohol? (Hint: ρeth = 790 kg/m3 and ρgly = 1360 kg/m3)
Problem 6
A tank containing methanol (of refractive index 1.40) has walls 2.50 cm thick made of glass
(which has a higher index of refraction). Light from the outside air (index of refraction 1.00)
strikes the glass at a 41.3o angle with the normal to the glass and then refracts into the
methanol. Find the angle the light makes with the normal in the methanol.
a. Draw an accurate diagram showing the path of the light ray for this situation.
b. Find the angle the light makes with the normal in the methanol.
Problem 7
A 1.0-cm-tall object is 10 cm in front of a converging lens that has a 30 cm focal length.
(i) Calculate the image position and height of the image, (ii) determine the image characteristics
using the magnification equation and (iii) draw a rough sketch of the ray trace diagram.
Problem 8
Use short concise sentences to answer the following questions using physics principles. Make
sure to explain your reasoning for each answer
a. You are driving down the road at a constant speed. Another car going a bit faster catches up
with you and passes you. Draw a (i) motion diagram and (ii) position graph for both vehicles
on the same set of axes, and note the point on the graph where the other vehicle passes
you?
b. Suppose you attempt to pour out 100 g of salt, using a pan balance for measurements,
while an elevator that is accelerating upward. Will the quantity (weight) of salt be too much,
too little, or the correct amount? Explain.
c. Automobiles are designed with "crumpled zones" intended to collapse in a collision. Why
would a manufacturer design part of a car so that it collapses in a collision? Draw a bar
diagram to explain your answer.
d. To change a tire, you need to use a jack to raise one corner of your car. While doing so, you
happen to notice that pushing the jack handle down 20 cm raises the car only 0.2 cm. Use
energy concepts to explain why the handle must be moved so far to raise the car by such a
small amount.
e. To explore the bottom of a 10-m-deep lake, your friend Tom proposes to get a long garden
hose, put one end on land and the other in his mouth for breathing underwater, and descend
into the depths. Susan, who overhears the conversation, reacts with horror and warns Tom
that he will not be able to inhale when he is at the lake bottom. Why is Susan so worried?
f. A lens can be used to start a fire by focusing an image of the sun onto a piece of flammable
material. All other things being equal would a lens with a short focal length or a long focal
length be better as a fire starter? Explain.
g. When you take clothes out of the drier right after it stops, the clothes often stick to your
hands and arms. Is your body charged? If so, how did it acquire a charge? If not, why does
this happen?