Question

29. What will be the work done required to increase the speed of a bike from 18 km/h to 54 km/h
if the mass of the bike is 100 kg?
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Answer 1

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Answer 2

Answer:

If a bike has a mass of 100 kg, the work done required to increase the speed of a bike from 18 km/h to 54 km/h is 10,000 J.

Explanation:

Given,

The total mass (m)   =  100 kg

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

Final speed  $\left(V_{f }\right)$      =  54 km/hr =  $54 \times\frac{5}{18} =\ 15 \ m/s$

According to the work-energy theorem,

Work done  =  Change in kinetic energy

Kinetic energy (K.E) can be expressed as,

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

So the change in K.E will be,

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

          =  $\frac{1}{2} \times 100 \times\left(\left\\15^{2}-\left\\5^{2}\right)$

          = 10,000 J

       

Ans:

The Work done   = 10,000 J