Answer:
h₍₁₎ = 495,1 meters
h₍₂₎ = 480,4 m
h₍₃₎ = 455,9 m
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Explanation:
The exercise is "free fall". t = 
Solving with this formula you find the time it takes for the stone to reach the ground (T) = 102,04 s
The heights (h) according to his time (t) are found according to the formula:
h(t) = 500 - 1/2 * g * t²
Remplacing "t" with the desired time.
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).
Objects should be cooled before their mass is determined on a sensitive balance because it could damage the balance. Also, because it would give you wrong reading of the mass. Hot objects would warm the air around it. A warm air would expand and would produce convection as it rises causing to give the object a mass that is less than the actual. Another reason would be it would cause instability in the readings, the mass would fluctuate every now and then due to the convection currents around the object. It is always recommended to weigh the masses of objects that are in room temperature.