Energy quiz 2001
AP Physics
NAMES ON BACK
Please do and show all work on a separate sheet of paper.
3 kg
1.7 m
1. In the picture above, a 3 kg block is placed next to a spring on spring constant 1000 N/m. The spring is
compressed and then released, causing the box to slide off of the table. Although the slide is frictionless,
the box does experience friction (µk=0.35) on the ground. The box travels 17 m before coming to a rest
on the ground.
a) How fast is the box travelling at the bottom of the slide?
b) How much was the spring compressed?
2) A graph of potential energy vs. position is
shown at right. A particle with energy 7 J is
located at x=0. (mass= 1kg)
10
5
U(J)
a) How fast is the particle moving?
b) How much kinetic energy will the
particle have at x=2 m?
c) Can the particle reach x=-2 m ?
Explain.
Potential Energy vs. Position
0
-4
-3
-2
-1
-5
0
1
2
3
4
-10
x(m)
3) A rectangular block is moving along a frictionless path when it encounters the circular loop as shown.
The block passes points 1,2,3,4,1 before returning to the horizontal track. At point 3:
a) its mechanical energy is a minimum
b) the forces on it are balanced
c) it is not accelerating
d) its speed is a minimum
e) it experiences a net upward force
4) The string in the figure is 50 cm long. When the ball is released from rest, it will swing along the dotted
arc. How fast, in m/s, will it be going at the lowest point in its swing?
a) 2.0 b) 2.2 c) 3.1 d) 4.4 e) 6.0
5) A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal
frictionless surface. When the spring is 4.0 cm shorter than its equilibrium length, the speed of the block
is 0.50 m/s. The greatest speed of the block is:
a) 0.23 m/s b) 0.32 m/s c) 0.55 m/s d) 0.71 m/s e) 0.93 m/s
6. A projectile of mass m is propelled from ground level with kinetic energy of 450 J. At the
exact top of its trajectory, its kinetic energy is 250 J. To what height above the starting
point does the projectile rise?
A) 450
B)
mg m
250
mg m
C)
700
mg m
D)
200
mg m
E)
350
mg m
7.
You ride a roller coaster car of mass 1500 kg down a frictionless track a distance H = 23m above
the bottom of a loop as shown. If the loop is 15 m in diameter, the downward force of the rails on
your car when it is upside down at the top of the loop is
Α) 4.6 × 104 N
B) 3.1 × 104 N
C) 1.7 × 104 N
D) 0.98 kN
E) 1.6 × 103 N