Question

2. A 4.0 kg ball moving to the right at 1.2 m/s collides inelastically with a 1.0 kg ball at rest. What will the velocity of the combined balls be after the collision?

3. An object is lowered into a deep hole in the ground. How does the potential energy of the object change?

4. A real spring does not oscillate forever. Instead, it eventually comes to a stop. Does this violate the Law of Conservation of Energy? Explain why or why not.

5. A boy can raise a rock that weighs 100 N by using a lever and applying a force of 20 N. What is the mechanical advantage of the lever?

Answer 1

2. in inelastic collision, the post-collision velocity will be identical; both balls will be moving together as one.

3. When the object is lowered the potential energy will decrease, it will be transferred to kinetic energy. Once it reaches the bottom of the deep hole, there will be no kinetic energy and as well as a net loss of potential energy.

4. No. Because according to Law of Conservation of Energy we have KEi+Eloss=0 and KE=-Eloss. The energy lost and the force that causes it to comes to a stop is friction. It is dissipated into forms of energy such as heat.

5. Fin = 20 N ; Fout = 100 N
MA = Fout / Fin = 100 N / 20 N = 5/1 = 5

Answer 2

2) 0.96 m/s

3) As the object is bee lowered the potential energy decreases.

4) It does not.

5) 5

Step-by-step explanation

Q2

Momentum for every collision is always conserved.

Moment = mass × velocity

Momentum before collision = momentum after collision

Momentum before collision = (4×1.2) + (1×0) = 4.8 Kgm/s

Momentum after collision = (4+1)V

Where V is the common velocity.

(4+1)V = 4.8

V = 4.8/5

= 0.96 m/s

Q3

Potential energy is the energy possessed by the virtue of its position relative to others. In this case, we are considering the end position of the object. As you lower the object you the relative distance decreases hence the potential energy decreases.

Q4

The law of conservation of energy is conserved in this case. The reason as to why to spring comes to a stop is that there is resistances that has to be overcome.Example the air resistance and the effect of gravitational force. Thus the spring can not continue oscillating forever.

Q5

Mechanical advantage (M.A) is the ration of load to effort. Load is the work done by the machine and effort is the work input in to the machine.

M.A = load/effort

= 100/20

= 5