PHYSICS-1305
CH-4
Name: _________________________________________
HOMEWORK CHAPTER-4: MOTIONS IN SPACE
Circle the correct answers
1.
What does the word centripetal mean?
(a) seeking the center
(b) fleeing the center
(c) being in the center
(d) being away from the center
2.
A monkey is sitting on a branch in a tree. A biologist wants to hit the monkey with a
tranquilizer dart. Where should she aim?
(a) directly at the monkey
(c) below the monkey
(b) above the monkey
3.
east?
(a)
(b)
(c)
What is the change in velocity if a car traveling east at 80 mph slows down to 60 mph
20 mph
20 mph west
20 mph east
(d) 70 mph west
(e) 70 mph east
4.
What is the average acceleration of a car that is traveling east at 60 mph and speeds up
to 80 mph east in 20 s?
(a) 20 mph
(d) 1 mph/s west
(b) 1 mph/s
(e) 3 mph/s
(c) 1 mph/s east
(f) 4 mph/s
5.
What is the average acceleration of a car that is traveling east at 80 mph and slows
down to 60 mph east in 20 s?
(a) 20 mph
(d) 1 mph/s west
(b) 1 mph/s
(e) 3 mph/s
(c) 1 mph/s east
(f) 4 mph/s
6.
A car travels east at 60 mph and then west at 40 mph. What is v?
(a) 20 mph west
(d) 60 mph east
(b) 20 mph east
(e) 100 mph west
(c) 60 mph west
(f) 100 mph east
7.
A car travels east at 60 mph and then north at 60 mph. What is v?
(a) 60 mph west
(d) 84 mph southeast
(b) 60 mph north
(e) 120 mph northwest
(c) 84 mph northwest
(f) 120 mph southeast
8.
A gun is fired horizontally. At the same time the bullet leaves the gun, an identical bullet is
dropped from the same height. Neglect air resistance. Which bullet hits the ground first?
(a) The bullet that was fired.
(c) It is a tie.
(b) The bullet that was dropped.
9.
Which bullet hits the ground first if this takes place on the Moon?
(a) The bullet that was fired.
(c) It is a tie.
(b) The bullet that was dropped.
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PHYSICS-1305
CH-4
10.
Which bullet hits the ground first if the mass of the dropped bullet has twice the mass of
the fired bullet?
(a) The bullet that was fired.
(c) It is a tie.
(b) The bullet that was dropped.
11.
(a)
(b)
(c)
(d)
When a ball is thrown,
its horizontal speed remains constant, but its vertical speed changes.
its horizontal and vertical speed both slow down at the same rate.
its vertical speed remains constant, but its horizontal speed changes.
its horizontal speed slows down much faster than its vertical speed.
A football quarterback throws a long pass toward the end zone. Assume that you can neglect
the effects of air resistance. The next two questions refer to the instant that the football reaches
the highest point of its path.
12.
What is the direction of the net force acting on the football?
(a) upward
(c) horizontal
(b) downward
13.
What is the direction of the acceleration of the football?
(a) upward
(c) horizontal
(b) downward
14.
A ball is fired horizontally at 4 m/s from the top of a very high cliff. What is the horizontal
speed of the ball at t = 3 s?
(a) zero
(d) 12 m/s
(b) 4 m/s
(e) 16 m/s
(c) 8 m/s
15.
A ball is fired horizontally at 4 m/s from the top of a very high cliff. What is the vertical
speed of the ball at t = 3 s?
(a) 15 m/s
(d) 30 m/s
(b) 20 m/s
(e) 35 m/s
(c) 25 m/s
16.
A ball is fired horizontally at 4 m/s from the top of a very high cliff. How far has the ball
fallen in these 3s?
(a) 15 m
(d) 45 m
(b) 25 m
(e) 55 m
(c) 35 m
17.
A ball is fired horizontally at 4 m/s from the top of a very high cliff. How far has the ball
traveled horizontally during these 3 s?
(a) 4 m
(d) 16 m
(b) 8 m
(e) 20 m
(c) 12 m
18.
A baseball has a horizontal speed of 30 m/s and a vertical speed of 15 m/s upward. One
second later the speeds are ___ horizontal and ____ vertical.
(a) 30 m/s ... 15 m/s
(c) 20 m/s ... 15 m/s
(b) 30 m/s ... 5 m/s
(d) 20 m/s ... 5 m/s
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PHYSICS-1305
CH-4
PROBLEMS
1a.
What is the change in velocity of a car that is initially travelling west at 50 km/hr and then
travels 20 km/hr towards East?
1b.
What is the acceleration of the car, if the change in velocity took 15 seconds.
3a.
Given the following: Mass of Moon= 7.4 x 1022 kg; Distance from earth to Moon = 3.8 x 108
m; and Moon takes 27 days to make one complete orbit around earth, calculate the centripetal
force of the Moon.
3b.
What is the value of the force of gravity between the earth and the Moon.
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PHYSICS-1305
CH-4
4a.
If a baseball is hit to that it has a vertical speed of 20 m/s, and a horizontal speed of 8
m/s, how long will the ball stay in the air?
4b.
How far from the home will it land on the ground?
5.
A ball is rolling on a table, and then falls off its edge. The speed of the ball just before it
leaves the table is 10 m/s, and it takes 0.25 seconds to hit the floor. How far from the table will it
hit the ground?
6.
A 20 kg child sits on a merry-go-round, at a point that is 3 m from its axis. The speed of the
child at that location is 2 m/s. What is his acceleration and centripetal force?
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