GENERAL PHYSICS I **EXAM 2**
NAME_______________________________________

3] A block of mass 2.0 kg is observed to slide down an incline at a
constant
velocity when the incline makes an angle of 30 degrees with the
horizontal.
What is the coefficient of kinetic friction between the block and
incline?

ANSW: 0.58

EXPLAIN BRIEFLY **which one** of __Credit will
be
given only if an explanation is included!} __NOTE: All 3 laws can be
applied
here but ONE will best describe the state of this object.

4] A mass of 0.50 kg is hanging vertically by a string. It is known that the string will break if the tension in it exceeds 25 N. What is the maximum acceleration that can be given to the mass by pulling up on the string?

ANSW: 40 m/s/s

Describe
the condition(s) that would be required for the tension in the string
to be
equal to zero.

**4] **You watch the following events happen while standing on
the shore.
Two sailing ships are passing your location. As you watch ship #1 pass
by,
moving at constant velocity, a stone is dropped from a tall mast of the
ship
and lands on its deck. Ship #2 passes by, moving with a constant
acceleration,
and a stone is also dropped from a tall mast landing on its deck.
EXPLAIN, with
reference to the appropriate laws of motion, where each stone (#1 and
#2) lands
relative to the mast from which it fell. {i.e., do they land at the
foot of the
mast or behind it?}

**5]** You are pulling a small child on a snow sled up a slope
that makes
a 30 degree angle with the horizontal . The
combined
mass of the child and sled is 20.0 kg. It is known that the coefficient
of
kinetic friction between the snow and sled is m
_{k} = 0.130 . If you pull the rope
such that
a constant force of 125 N is acting on the sled parallel to the surface
of the
slope, what is the acceleration of the sled/child combination **up**
the
incline?

ANSW: +.245 m/s/s

**1]** A 2.50 gm bullet passes through a
material
that is 1.25 cm thick. The bullet enters

the material with a velocity
of 350
m/s and exits the material with a velocity of 250 m/s.

Find the work done on the
bullet by
friction as it passes through the material and the

average force of friction on
the
bullet.

Answer: W(fric) = - 75.0 J F(fric) = 6000 N

**2]** A 2.00 kg block
sliding
down a frictionless ramp has a velocity of 0.50 m/s when at a

height ,
h
, above a level surface. The block slides to the bottom of the ramp and
continues

to slide a short distance
along a
level (frictionless) surface until it comes to rest after

compressing a spring a
distance of
1.50 cm. The spring constant is k = 4.6 x 10^{4} N/m.

Find the height, h
, for the block. {NOTE: the angle of the ramp and length of the
ramp are

unknown!}

Answer: 0.25 m

1] A skier with a mass of 60.0 kg has a
speed of
3.50 m/s when they are at a vertical height 24.0 m

above the bottom of a hill.
If a
constant frictional force of 70.0 N opposes their motion down the

hill and the length of the
slope is
65.0 m, what is their speed at the bottom of the hill?

Answer: 18.2 m/s

2] A spring with spring constant k = 75.0
N/m is
used to launch a projectile of mass 100 gm straight

up. If the spring is
compressed 12.5
cm in order to launch the projectile, how high above this

compressed spring point is
the
projectile when it has a speed of +1.50 m/s? (Neglect friction for

this problem!)

Answer: 0.483 m

**SAMPLE
MULTIPLE CHOICE**

1) A packing crate slides
down an
inclined ramp at constant velocity. Thus, we can deduce that

a) a frictional force is acting on it.

b) a net downward force
is acting
on it.

c) it may be
accelerating.

d) it is not acted on by
an
appreciable gravitational force.

2) When you sit in a chair, the sum of all the forces acting on
you while
you sit

a) is up

b) is down

c) depends on your weight

d) is zero

3) If you blow up a balloon and then release it, the balloon will
fly
away. This is an illustration of

a) Newton's 1st law

b) Newton's 2nd law

c) Newton's 3rd law

d) the law of gravity

4) A mass is suspended from the ceiling by means of a string. The
Earth
pulls downward on the mass with the weight force

of the mass equal to 8
N. If
this is the "action" force of the 3rd law, what is the
"reaction" force?

a) the string pulling upward on the mass with an 8 N
force

b) the ceiling pulling upward on the string with an
8 N
force

c) the string pulling downward on the ceiling with
an
8 N force

d) the mass pulling upward on the Earth with an 8 N
force

5) According
to the scientific definition of
work, pushing on a rock accomplishes no

work unless there
is

A) an applied force
greater than its weight.

B) a net force
greater than zero.

C) an opposing
force.

D) movement in the
same direction as the force.

6)
The potential energy of a box on a shelf,
relative to the floor, is a measure of

A) the work done
putting the box on the shelf from the floor.

B) the weight of the
box times the distance above the floor.

C) the energy the
box has because of its position above the floor.

D) any of these

7)
Which quantity has the greatest influence on
the amount of kinetic energy that a large

truck has
while moving down the highway?

A) mass

B) weight

C) velocity

D) size

8)
The law of conservation of energy is a
statement that

A) energy must be
conserved and you are breaking a law if you waste energy.

B) the supply of
energy is limited so we must conserve.

C) the total amount
of energy is constant.

D) energy cannot be
used faster than it is created.

**SAMPLE
MULTIPLE
CHOICE QUESTIONS FOR MOTION AND **

2)
d

3)
c

4)
d

5)
d

6)
d

7)
c

8)
c