Question

What is the work to be done to increase the velocity of a bike from 10 km/hr to 30 km / hr if the mass of the bike is 100kg​

Answer 1

Work on a body = force

Mass = 100kg

Force = Mass/Velocity

Velocity we are increasing = 30 - 10

=20km/h (20 km)

So,

= 100/20

=5 N (newton) is the work done

Answer 2

Answer:

If the mass of the bike is 100kg, the work to be done to increase the velocity of a bike from 10 km/hr to 30 km /hr  is 3086.4136 J

Explanation:

Given,

The total mass (m)   =  100 kg

Initial speed  $\left(V_{i}\right)$      =  10 km/hr = $10 \times\frac{5}{18} =\ 2.7777 \ m/s$

Final speed  $\left(V_{f }\right)$      =  30 km/hr =  $30 \times\frac{5}{18} =\ 8.3333 \ m/s$

According to the work-energy theorem, work done will be equal to the change in kinetic energy.

Work done  =  Change in kinetic energy

So we have to find out the change in K.E  to calculate work done.

We have the expression for Kinetic energy (K.E) as,

$\mathrm{K} . \mathrm{E}=\frac{1}{2} m V^{2}$

So the change in K.E will be,

$\Delta \mathrm{KE}=\frac{1}{2} \mathrm{~m}\left(\mathrm{~V}_{\mathrm{f}}^{2}-\mathrm{V}_{\mathrm{i}}^{2}\right)$

          =  $\frac{1}{2} \times 100 \times\left(\left\\8.3333^{2}-\left\\2.7777^{2}\right)$

          = 3086.4136 J

         

Ans:

The Work done   = 3086.4136 J