Answer
given,
mass of the piano = 170 kg
angle of the inclination = 20°
moves with constant velocity hence acceleration = 0 m/s²
neglecting friction
so, force required to pull the piano
F = m g sin θ
F = 170 × 9.81 × sin 20°
F = 570.39 N
so, force required by the man to push the piano is F = 570.39 N
The amount or cost that the user of the energy-efficient bulb save during 100h of use will be $0.319.
<h3>How to calculate the cost?</h3>
For the 11.0W bulb, it should be noted that the value will be:
= 11.0 × 100 × (1/1000) × 0.110
= $0.121
The 40W bulb will be:
= 40 × 100 × (1/1000) × 0.110
= $0.44
Therefore, the amount that will be saved will be:
= $0.44 - $0.121
= $0.319
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<span>At the top of the waterfall, the water has potential energy. Once it goes over</span>
Momentum = mass x velocity, so 500kg x 2m/s = 1000 kg m/s