Question

What will be the mass of A Car moving with velocity of 68 km/h applies brakes And attains new velocity of 42km/h in 5 sec . When 35 Newton's Force is applied .
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Answer 1

Answer:

A driver of a car travelling at 52km h−1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5s. Another driver going at 3km h−1 in another car applies his brakes slowly and stops in 10s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?

Explanation:

Solution



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(A)   :         Initial speed of the car A      u=52  kmh−1=52×185=14.44  ms−1

               The car stops in 5 seconds        i.e     v=0  at  t=5

(A)   :         Initial speed of the car A      u=3  kmh−1=3×185=0.83  ms−1

               The car stops in 10 seconds        i.e     v=0  at  t=10

With the help of these initial and final points for both the cases,  we can plot the graph of speed vs time.

Area under the speed-time graph gives the distance covered.

∴   Distance covered by car A       xA=21×14.44×5=36.1 m

∴   Distance covered by car A       xB=21×0.83×10=4.15 m