An automobile travelling with speed...
Question

An automobile travelling with speed of 60 km/h, can brake to stop within a distance of 20 cm. If the car is going twice as fast, i.e. 120 km/h, the stopping distance will be [AIEEE-2004) (A) 20 m (B) 40 m (D) 80 m om

JEE/Engineering Exams
Physics
Solution
179
4.0 (1 ratings)
An Automobile travelling with seeed of ( 60 mathrm{km} / mathrm{m} ) an brake twice as fast in ( mathrm{RO} mathrm{km} / mathrm{m} ) the Stopping distenk will be [ 80 mathrm{m} ] Given the t option intialspeed ( u=60 mathrm{km} / mathrm{h} ) [ begin{array}{l} v=0 s=20 m=20 eta 1000 m=0.02 mathrm{km} end{array} ] Acudding to kenemotic equebons of mobons Given thef [ begin{array}{l} v^{2}-u^{2}=2 a s 0^{2}-60^{2}=2(a)(0.02) -3600=0.04 a a=-frac{3600}{0.04} =frac{-3600}{100}=frac{3600 times 100}{4} end{array} ] speed becomes fortwice [ -90000 mathrm{km} / mathrm{n}^{2} ] there [ c=120 mathrm{km} / mathrm{hr} ] speed [ begin{array}{l} v=0 a=-90000 mathrm{km} 14^{2} end{array} ] Welove to find the ( theta ) stopping distance ( (s)=? )