Question

1a. Give 6 examples where Energy is Conserved in an event.
1b. Give 6 examples where Energy is NOT Conserved in an
event.
1c. Give 2 examples of an event where Momentum is NOT
Conserved.

Answer 1

1. Total Energy is conserved in most cases of work done, for example-

i) A ball falls from some height to ground.

ii) A ball rolls down the frictionless incline.

iii) water energy turns into electricity .

iv) A book is pushed across the table.

v) A puck is hit by bat.

vi) A moving car collides with a parked car and causes it to move.

2.Total Energy is not conserved work is done due to non-conservative forces like friction, for example-

i) A car skids on wet surface.

ii) A ball rolls down the incline with friction.

iii) A box is pulled across the rough surface .

iv) An inelastic collision where two objects joined together after collision.

v) A coin sliding on a table.

vi) A moving car collides with a parked car and causes it to heat up due to friction and drag.

3. Momentum is not conserved in case of friction and gravity.

i) A block collides with another block that is attached with spring. After collision, both blocks stuck together and oscillate.

ii) Two pendulums collide at the bottom. Momentum is not conserved due to gravity.