Answer: 1026s, 17.1m
Explanation:
Given
COP of heat pump = 3.15
Mass of air, m = 1500kg
Initial temperature, T1 = 7°C
Final temperature, T2 = 22°C
Power of the heat pump, W = 5kW
The amount of heat needed to increase temperature in the house,
Q = mcΔT
Q = 1500 * 0.718 * (22 - 7)
Q = 1077 * 15
Q = 16155
Rate at which heat is supplied to the house is
Q' = COP * W
Q' = 3.15 * 5
Q' = 15.75
Time required to raise the temperature is
Δt = Q/Q'
Δt = 16155 / 15.75
Δt = 1025.7 s
Δt ~ 1026 s
Δt ~ 17.1 min
The time
it takes for the key to fall 44 m is

(notice I'm taking the downward direction to be positive)
The boat, moving at a presumably constant speed, then has 3.0 s to travel 19 m to the point of impact, which means its speed must be

Answer:
They can expect the size of the rocks to get smaller as the time passes.
Explanation:
They can expect the size of the rocks to get smaller as the time passes.
- This is so because the water falling from certain height under waterfall will exert mechanical impact on the rock due to the mass of the water. This will act as water hammer <em>causing wear and tear</em> to the rock particles and flowing them away with the stream of water.
- This hydraulic shock is generated when there is sudden stoppage in the motion of water. In sync with Newton's second law of motion, when the momentum of water is changed within a short course of time it creates a hammer like impact which has potential of wear and tear when an object is continuously subjected to it.