Physics Homework 18 questions I need them after 5:30 hours HELP ME !!!

homework 07 – KHALEEFOH, FAHAD – Due: Apr 7 2017, 11:00 pm (Central time) 1

Question 1, chap 8, sect 4.

part 1 of 3 10 points

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 as-

sociated 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.

homework 07 – KHALEEFOH, FAHAD – Due: Apr 7 2017, 11:00 pm (Central time) 2

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.