Question

A bicyclist was moving at a rate of 8 m/s, and then sped up to 10 m/s. If the cyclist has a mass of 120 kg, how much work was needed to increase his velocity? (Hint: Use the work-kinetic energy theorem.)

Answer 1

Answer:

Work = 2160 J

Explanation:

As per work energy theorem we know that work done is equal to the change in the kinetic energy of the cyclist.

As the cyclist is initially moving at speed 8 m/s and after some time his speed changes to 10 m/s

So here we can say that

final kinetic energy - initial kinetic energy = work done

$W = \frac{1}{2}m(v_f^2 - v_i^2)$

now by plug in all values

$W = \frac{1}{2}(120)(10^2 - 8^2)$

$W = 2160 J$

so work done by cyclist will be 2160 J

Answer 2

W=∆KE

KE=1/2m∆v^2

=1/2*120*(10-8) ^2

=240j