Question 93: Motion in 1D

Question

An automobile travelling with speed of 60 km/h, can brake to stop within a distance of 20 m.
If the car is going twice as fast, i.e 120 km/h, the stopping distance will be

Accepted Answer

Assume $$a$$ be the retardation for both the vehicle then
In case of automobile,
$$u_1^2 - 2a{s_1} = 0$$
$$ \Rightarrow u_1^2 = 2a{s_1}$$
And in case for car,
$$u_2^2 = 2a{s_2}$$
$$	herefore$$ $${\left( {{{{u_2}} \over {{u_1}}}} ight)^2} = {{{s_2}} \over {{s_1}}}$$
$$ \Rightarrow {\left( {{{120} \over {60}}} ight)^2} = {{{s_2}} \over {20}}$$
$$ \Rightarrow$$ s
2
= 80 m

Answer

60 m

Answer

40 m

Answer

20 m

Answer

80 m

Motion in 1D

An automobile travelling with speed of 60 km/h, can brake to stop within a distance of 20 m. If the car is going twice as fast, i.e 120 km/h, the stopping distance will be

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