Starting from rest and height of 7 m, a 3kg object slides down a 30degrees incline, reaching the bottom with a speed of 10m/s . what is the work done by friction? elaborate.

The work done by the friction is 55.8 J.

Explanation:

Given that,

Height h = 7 m

Mass of the object = 3 kg

Angle = 30°

Speed = 10 m/s

The initial potential energy of the object is converted in to the kinetic energy at the bottom of the incline and  the work done by the friction

Where, m = mass of the object

v = final velocity

g = acceleration due to gravity

h = height

Put the value in the equation

Hence, The work done by the friction is 55.8 J.

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explanation:

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle