A student removes a 10.5 kg stereo amplifier from a shelf that is 1.82 m high. The amplifier is lowered at a constant speed to a height of 0.75 m. What is the work done by (a) the person and (b) the gravitational force that acts on the amplifier

(a) the work done by the student is 110.1 J

(b) The gravitational force that acts on the amplifier is 102.9 N

Explanation:

Given;

mass of the amplifier, m = 10.5 kg

initial position of the amplifier, x₀ = 1.82 m

final position of the amplifier, x₁ =0.75 m

The dispalcement of the amplifier Δx = x₁ - x₀ = 1.82 m - 0.75 m = 1.07 m

(b) The gravitational force that acts on the amplifier;

F = mg

F = 10.5 x 9.8

F = 102.9 N

(a) the work done by the student is calculated as;

W = FΔx

W = 102.9 x 1.07

W = 110.1 J

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

the body's situation won't change the forces are equal opposit and on the same body