Answer:
c. 1600J
Explanation:
The loss in potential energy of the boy is given by:

where
m = 40 kg is the mass of the boy
g = 9.8 m/s^2 is the acceleration of gravity
is the total change in the height of the boy (4 metres + 2 cm due to the compression of the spring)
Substituting, we find

By using ramps you can easily push or pull the object up the ramp.
Sound travels through solids the fastest
Hope it helps...
1. Most PE, because PE is directly proportional to distance (height)
Height: 100 meters
Speed: 0 mph
2. Most KE, because KE is directly proportional to speed
Height: 10 meters
Speed: 40 mph
3. Most TE, average KE
Height: 10 meters
Speed: 40 mph
4. The skater gains thermal energy as she goes down the slope, because the speed of the skater increases, so it increases the total kinetic energy of the particles, and makes them vibrate faster, resulting in a higher temperature.