©Prep101
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1.
A girl throws a ball at a vertical wall 4 m
away (as shown in the diagram). The ball is
2 m above the ground when it leaves the
girl’s hand with an initial velocity of v0
14.14m/s and an angle 45
o
above the
horizontal (v
x
=10m/s and v
y
= 10m/s).
When the ball hits the wall, the horizontal
component of its velocity is reversed, while
the vertical component remains unchanged.
How far from the wall does the ball hit the
ground?
a.
19.3 m
b.
18.2 m
c.
17.0 m
d.
15.9 m
2.
A stone of mass
m
is attached to a light strong
string and whirled in a vertical circle of radius
r
.
At the exact bottom of the path the tension
in the string is three times the stone’s weight.
The stone’s speed is given by:
a.
gr
2
b.
gr
2
c.
2
gr
d.
4
gr
3.
A small magnet of mass 1 g is levitated by a
piece of superconductor.
What is the force the
magnet exerts on the superconductor? (g = 10
m/s
2
)
a.
0 N
b.
0.001 N
c.
0.01 N
d.
1 N
4.
Two large crates m
1
and m
2
are connected to
each other by a stiff massless spring. The force
constant of the spring “k” is 8000 N/m, m
1
is
650 kg, and m
2
is 490 kg. A constant
horizontal force “F” is applied to m
1
which
ultimately gives the two masses and the spring
a common acceleration on the frictionless
floor. If the spring is compressed 5 cm from
its initial unstretched length during the motion,
what is the magnitude of the applied force F?
a.
931 N
b.
815 N
c.
759 N
d.
591 N
5.
In an experiment with a block of wood on an
inclined plane, with dimensions shown in the
figure below, the following observations are
made:
1) If the block is placed on the inclined plane,
it remains there at rest.
2) If the block is given a small push, it will
accelerate toward the bottom of the incline
without any further pushing.
Which is the best conclusion that can be
drawn from these observations?
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