Question

7. An automobile travelling with a speed of 60 km/h, can brake to stop within a distance of 20 m. If the car is going twice as fast, ie 120 km/h, the stopping distance will be [AIEEE 2004, 4/300)

JEE/Engineering Exams

Physics

Solution

125

4.0 (1 ratings)

Fa automolile [ begin{array}{l} V^{2}=u^{2}-2 a b therefore u_{1}^{2}-2 a s=0 u_{1}^{2}=2 a b_{1} end{array} ] Fa car [ u_{2}^{2}=2 a s_{2} ] [ begin{array}{l} left(frac{u_{2}}{u_{1}}right)^{2}=frac{S_{2}}{s_{1}} quadleft(frac{120}{60}right)^{2}=frac{s_{2}}{20} Rightarrow s_{2}=80 mathrm{m} end{array} ]