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Chapter 3
1) Ten seconds after starting from rest, an object falling freely
downward will have a speed of about
A) 10 m/s.
a = Δv / Δt
B) 50 m/s.
10 = Δv / 10
C) 100 m/s.
D) more than 100 m/s.
2) An object travels 8 meters in the first second of travel, 8
meters again during the next second of travel, and 8 meters
again during the third second. Its acceleration is
A) 0 m/s2.
a = Δv / Δt
B) 5 m/s2.
a = (8-8) / 3
C) 8 m/s2.
D) 10 m/s2.
E) more than 10 m/s2.
3) It takes 6 seconds for a stone to fall to the bottom of a mine
shaft. How deep is the shaft?
A) about 60 m
d = ½ a t2
B) about 120 m
d = ½ 10 62
C) about 180 m
d = 180 m
D) more than 200 m
4) If you drop an object, it will accelerate downward at a rate
of 9.8 meters per second per second. If you instead throw it
downwards, its acceleration (ignore air resistance) will be
A) less than 9.8 meters per second per second.
B) 9.8 meters per second per second.
C) greater than 9.8 meters per second per second.
5) A car accelerates at 2 meters per second per second.
Assuming the car starts from rest, how much time does it need
to accelerate to a speed of 30 m/s?
A) 2 seconds
a = Δv / Δt
B) 15 seconds
2 = 30 / Δt
C) 30 seconds
t = 15 sec
D) 60 seconds
E) none of these
6) When a rock thrown straight upwards gets to the exact top
of its path, its
A) velocity is zero and its acceleration is zero.
B) velocity is zero and its acceleration is about 10 meters per
second per second.
C) velocity is about 10 m/s and its acceleration is zero.
D) velocity is about 10 m/s and its acceleration is about 10
meters per second per second.
E) none of these.
7) A ball is thrown 125 meters upward and then falls the same
distance back to Earth. Neglecting air resistance, its total time
in the air is about
A) 5 seconds.
d = ½ a ttop2
B) 10 seconds.
125 = ½ 10 ttop2
C) 15 seconds.
ttop = 5 sec
D) more than 20 seconds.
ttop + tbottom = 10 sec
8) A man leans over the edge of a cliff and throws a rock
upward at 4.9 m/s. Two seconds later the rock's speed is
A) zero.
a = Δv / Δt
B) 4.9 m/s.
-9.8 = (0 – 4.9) / ttop
C) 9.8 m/s.
ttop = ½ s so tbottom = (2 – ½)
D) 14.7 m/s.
9.8 = (vf – 0) / 1.5 sec
E) none of the above.
vf = 14.7 m/s
Chapter 4
9) Strange as it may seem, it is just as hard to accelerate a car
on the moon as it is to accelerate the same car on Earth. This is
because
A) the mass of the car is independent of gravity.
B) the weight of the car is independent of gravity.
C) ...Nonsense! A car is much more easily accelerated on the
moon than on the Earth.
10) In which case would you have the largest mass of gold? If
your chunk of gold weighed 1 N on the
A) moon.
FW-moon = m g
B) Earth.
1 N = m (1/6 * 10 m/s2)
C) planet Jupiter.
mmoon = 3/5 kg
11) An object is propelled along a straight-line path by a force.
If the net force were doubled, the object's acceleration would
A) quadruple.
F=ma
B) double.
2F = m (2a)
C) stay the same.
D) halve.
E) none of these.
12) An object is pulled northward with a force of 10 N and
southward with a force of 15 N. The magnitude of the net force
on the object is
A) 0 N.
FNet = 15 + -10
B) 5 N.
FNet = 5 N
C) 10 N.
D) 15 N.
E) none of these.
13) The maximum acceleration of a car while towing a second car
twice its mass, compared to no towing, is
A) one half.
Fengine = m a
B) one third.
Fengine = (2m + m) (a / 3)
C) one fourth.
D) the same.
E) none of these.
14) A car has a mass of 1000 kg and accelerates at 2 meters per
second per second. What is the magnitude of the net force
exerted on the car?
A) 500 N
F=ma
B) 1000 N
F = (1000kg) (2 m/s2)
C) 1500 N
F = 2000 N
D) 2000 N
E) none of these
15) A bag of groceries has a mass of 10 kilograms and a weight
of about
A) 1 N.
FW = m
g
B) 10 N.
FW = 10kg (10m/s2)
C) 100 N.
FW = 100 N
D) 1000 N.
E) more than 1000 N.