1. A wheelchair ramp. Instead of using lifting force on the wheelchair, You use push or pull force on it.
2. A slide. Instead of throwing down an item, It uses gravitational potential energy make an object "move" down the slide.
3.A screw. It's reducing the force by twisting the screw out of something instead of pulling it out. (Sorry about my bad grammar).
3. Sand has a low specific heat compared to air
I think F= mv²/r
And F=ma
So, ma = mv²/r
a = v²/r
a = 100/5
a = 20 m/s
Explanation:
1. Force applied on an object is given by :
F = W = mg
(a) A 160 lb human being, F = 160 lb
g = acceleration due to gravity, g = 32 ft/s²


m = 5 kg
(b) A 1.9 lb cockatoo, F = 1.9 lb


m = 0.059 kg
2. (a) A 2300 kg rhinoceros, m = 2300 kg

(b) A 22 g song sparrow, m = 22 g = 0.022 kg

Hence, this is the required solution.