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Exam 1 PH201
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------------------------------------------------------------
Multiple Choice: 2 points for each question (26 total)
Partial Credit 8 points for each problem (24 total)
Extra Credit 2 points => Your grade% = score out of 48 points
----------------------------------------------------------------
Partial Credit: Please write clearly. Write down all equations you
use. Sloppy work results will lead to point deduction. Choose 3 out of
4 partial credit problems. If you do all four the highest three scores
count.
---------------------------------------------------------------------Constants:
Gravitational constant: G = 6.67 10-11 m3kg1 s-2, Radius earth 6,378.135 km
Acceleration of gravity (close to earth’s surface): g= 9.8 m/s2
PHY21 Exam1
Version #1
Student: ___________________________________________________________________________
1.
An airplane is traveling in level flight at a constant velocity. L is the lift, W is the weight, T is the thrust,
and D is the drag. Which of the diagrams is the correct free body force diagram for the airplane?
A.
B.
C.
D.
E.
2.
Figure 5
Figure 2
Figure 4
Figure 3
Figure 1
A ball thrown into the air follows a parabolic trajectory. At the highest point in the trajectory:
A.
B.
C.
D.
both the velocity and the acceleration are zero.
the velocity is zero, but the acceleration is not zero.
neither the acceleration nor the velocity are zero.
the acceleration is zero but he velocity is not zero.
1
3.
A tractor (T) is pulling a trailer (M) with a constant velocity. If the velocity is 20 m/s and M = 200 kg
and T = 500 kg, then the force on the trailer due to the tractor is:
A.
B.
C.
D.
E.
4.
The net force on a moving object suddenly becomes zero. The object then:
A.
B.
C.
D.
E.
5.
changes direction.
slows down gradually.
stops during a short time interval.
continues at constant velocity.
stops abruptly.
If an object is located 20 m to the right of the origin at 1:00 PM and later the object is located 30 m to
the left of the origin at 2:00 PM, then the displacement from 1:00 PM to 2:00 PM is:
A.
B.
C.
D.
E.
6.
600 N forward.
450 N backward.
200 N backward.
0.
35 N forward.
30 m to the left.
50 m to the left.
10 m to the left.
30 m to the right.
50 m to the right.
An object of mass m is hanging by a string from the roof of an elevator. The elevator is increasing its
upward speed. What is the tension in the string?
A.
B.
C.
D.
Depends on the speed of the elevator.
Greater than mg
Less than mg
Equal to mg
2
7.
A 3.0 kg ball is thrown vertically into the air with an initial velocity of 15.0 m/s. The time it takes the
ball to reach its maximum height is:
A.
B.
C.
D.
E.
8.
A car traveling at 3.0 m/s has a constant acceleration of 4.0 m/s2. After 2.0 seconds, the velocity is:
A.
B.
C.
D.
E.
9.
1.3 s.
0.8 s.
0.9 s.
1.5 s.
1.2 s.
5.0 m/s.
11 m/s.
7.0 m/s.
13 m/s.
9.0 m/s.
Ball A is dropped from the top of a building. One second later ball B is dropped from the same point. As
time progresses, the distance between them:
A.
B.
C.
D.
remains constant.
need more information.
increases.
decreases.
10. Two masses are connected by a string which passes over a pulley with negligible mass and friction. One
mass hangs vertically and one mass slides on a 30.0 degree frictionless incline. The vertically hanging
mass is 3.00 kg and the mass on the incline is 6.00 kg. The acceleration of the 4.00 kg mass is (the initial
velocity is zero):
A.
B.
C.
D.
E.
6.72 m/s2.
2.98 m/s2.
1.03 m/s2.
0.00 m/s2.
7.48 m/s2.
3
11. Which of the following is a vector quantity?
A.
B.
C.
D.
E.
Time
Volume
Force
Speed
Length
12. When a person stands on a scale, which of the following is not a force exerted on the scale?
A.
B.
C.
D.
A contact force due to the person's feet.
The weight of the scale.
The weight of the person.
A contact force due to the floor.
13. A space probe leaves the solar system to explore interstellar space. Once it is far from any stars, when
must it fire its rocket engines?
A.
B.
C.
D.
E.
Only when it wants to turn.
When it wants to speed up, slow down, or turn.
All the time, in order to keep moving.
Only when it wants to speed up.
Only when it wants to slow down.
4
1. A projectile is launched with an initial speed of 30 m/s at an angle of 60°
above the horizontal. What are the (a) magnitude and (b) angle of its
velocity 2.0 s after launch, and (c) is the angle above or below the
horizontal? What are the (d) magnitude and (e) angle of its velocity 5.0 s
after launch, and (f) is the angle above or below the horizontal?
(a,b,d,e 1.5 Points ; c,f 1 Point)
2. During volcanic eruptions,
chunks of solid rock can be blasted
out of the volcano; these
projectiles are called volcanic
bombs. The Figure shows a cross
section of Mt. Fuji, in Japan. (a) At
what initial speed would a bomb
have to be ejected, at angle 45° to
the horizontal, from the vent at A
in order to fall at the foot of the
volcano at B, at vertical distance d=790m and horizontal distance of d = 2km
? Ignore, for the moment, the effects of air on the bomb’s travel. (b) What
would be the time of flight? (c) Would the effect of the air increase or
decrease your answer in (a)? (a) 5 Points, b) 2 Points c) 1Point)
3. In the overhead view of the Figure, five
forces pull on a box of mass m = 4.0 kg. The
force magnitudes are F1 = 11 N, F2 = 17 N, F3
= 3.0 N, F4 = 14 N, and F5 = 5.0 N, and angle
θ4 is 30°. Find the box’s acceleration (a) in unitvector notation and as (b) a magnitude and (c)
an angle relative to the positive direction of the
x axis. ( a) 4Points , b) 2Points, c) 2Points )
4. In the Figure, a 49 kg rock climber is climbing a
“chimney.” The coefficient of static friction between
her shoes and the rock is 1.2; between her back and
the rock is 0.80. She has reduced her push against the
rock until her back and her shoes are on the verge of
slipping. (a) Draw a free-body diagram of her. (b)
What is the magnitude of her push against the rock?
(c) What fraction of her weight is supported by the
frictional force on her shoes?