Hello,

Solution for the question is given below:

j=4200j/kcal (given)

g=10m/s2 (given)

Work Done=F*displacement Coefficient of friction*m*g*(v*t)W

=0.5*21*10*(20*36500)

=7,560,000

Heat Generated=7,560,000/4186

=806.02 w

Thank You!

Hello,

We know that heat generated by the body will be the total work done by the body.

And, work done by the body is given by the relation, W = Force * Displacement

Also, Force = coefficient of friction * mass * acceleration due to gravity

Therefore, W = coefficient of friction * mass * acceleration due to gravity * displacement (Equation 1)

Now, Coefficient of friction = 0.5 (Given)

Mass = 21 KG (Given)

Acceleration due to gravity = 10 m/s^2 (Given)

Speed = 20 Km/hr, therefore distance travelled in 1 hour will be: 20Km = 20000 m (Given)

Now substituting the values in Equation 1, we get:

W = 0.5 * 21 * 10 *20000 = 2.1 * 10^6 J (Answer)

Also, we know, 1 kcal = 4200 J

Therefore, work done = (2.1 * 10^6) /4200 = 500 kcal (Answer)

Hope it is clear to you!