1. An example of negative work.

Question

2. An example of conservation of energy
3. An example of kinetic being converted to heat and sound

Answer 1

1. Stopping a wheelbarrow.
2. Falling one meter with mass of m kg on earth if g = 9.8 m/s^2
total energy at top is potential relative to ground = m g h = m*9.8*1 = 9.8 m Joule
total energy at bottom = 9.8 m Joule still but now all kinetic
9.8 m Joule = (1/2) m v^2
v^2 = 2 g
v^2 = 2
v = sqrt 2 m/s^2

Answer 2

delete last two lines, they assume g = 1

Answer 3

3. Let asteroid hit earth atmosphere and burn up, lighting up the sky.

Answer 4

thanks damon