A 39.0 kg child is in a swing that is attached to ropes 1.60 m long. The acceleration of gravity is 9.81 m/s2 . Find the gravitational potential energy associated with the child relative to the child’s lowest position under the following condi- tions: a) when the ropes are horizontal.

A 39.0 kg child is in a swing that is attached to ropes 1.60 m long. The acceleration of gravity is 9.81 m/s2 . Find the gravitational potential energy associated with the child relative to the child’s lowest position under the following condi- tions: a) when the ropes are horizontal.
Answer in units of J.
Question 2, chap 8, sect 4.
part 2 of 3 10 points
b) when the ropes make a 37.0◦ angle with the vertical. Answer in units of J.
Question 3, chap 8, sect 4.
part 3 of 3 10 points
c) at the bottom of the circular arc. Answer in units of J.
Question 4, chap 8, sect 4.
part 1 of 3 10 points
A 54 kg skier is at the top of a slope, as in the figure. At the initial point A, the skier is 7.08 m vertically above the final point B. The acceleration of gravity is 9.81 m/s2 .
7.08 m
a) Find the difference in gravitational po- tential energy associated with the skier at the points A and B if the zero level for gravita- tional potential energy is at point B. Answer in units of J.
Question 5, chap 8, sect 4.
part 2 of 3 10 points
b) Find the difference in potential energy if the zero level is at point A. Answer in units of J.
Question 6, chap 8, sect 4.
part 3 of 3 10 points
c) Find the difference in potential energy if the zero level is midway down the slope, at a height of 3.54 m. Answer in units of J.
Question 7, chap 8, sect 4.
part 1 of 3 10 points
A 1.8 kg ball is attached to a ceiling by a 3.94 m long string. The height of the room is 5.18 m . The acceleration of gravity is 9.8 m/s2 . What is the gravitational potential energy
associated with the ball relative to the ceiling? Answer in units of J.
Question 8, chap 8, sect 4.
part 2 of 3 10 points
What is its gravitational potential energy relative to the floor? Answer in units of J.
Question 9, chap 8, sect 4.
part 3 of 3 10 points
What is its gravitational potential energy relative to a point at the same elevation as the ball? Answer in units of J.
Question 10, chap 8, sect 5.
part 1 of 1 10 points
In an arcade game a 0.09 kg disk is shot across a frictionless horizontal surface by com- pressing it against a spring and releasing it. If the spring has a spring constant of
248 N/m and is compressed from its equi- librium position by 4 cm, find the speed with which the disk slides across the surface. Answer in units of m/s.
Question 11, chap 8, sect 5.
part 1 of 3 10 points
A(n) 139 g arrow is shot straight up into the air with a speed of 16 m/s. It reaches a maximum height of 12.0612 m. The acceleration of gravity is 9.8 m/s2 . Find the initial kinetic energy.
Answer in units of J.
Question 12, chap 8, sect 5.
part 2 of 3 10 points
Find the potential energy at its highest position. Answer in units of J.
Question 13, chap 8, sect 5.
part 3 of 3 10 points
Find the magnitude of the energy lost due to air resistance. Answer in units of J.
Question 14, chap 8, sect 5.
part 1 of 2 10 points
A bead slides without friction around a loop-the-loop. The bead is released from a height 24.2 m from the bottom of the loop- the-loop which has a radius 9 m. The acceleration of gravity is 9.8 m/s2 .
24.2 m 9 m
A
What is its speed at point A ? Answer in units of m/s.
Question 15, chap 8, sect 5.
part 2 of 2 10 points
How large is the normal force on it at point A if its mass is 4 g?
Answer in units of N.
Question 16, chap 8, sect 5.
part 1 of 3 10 points
A block starts at rest and slides down a fric- tionless track (as shown in the figure below). It leaves the track horizontally, flies through
the air, and subsequently strikes the ground. The acceleration of gravity is 9.81 m/s2 .
b b b b b b
b b
b b
b
b
434 g
4 .6
m
2 .3
m
x
9 .8 1 m / s2
v
What is the speed v of the ball when it leaves the track? Answer in units of m/s.
Question 17, chap 8, sect 5.
part 2 of 3 10 points
What is the horizontal distance x the block travels in the air? Answer in units of m.
Question 18, chap 8, sect 5.
part 3 of 3 10 points
What is the speed of the block when it hits the ground? Answer in units of m/s