Question 95: Motion in 1D

Question

A car, moving with a speed of 50 km/hr, can be stopped by brakes after at least 6 m. If the
same car is moving at a speed of 100 km/hr, the minimum stopping distance is

Accepted Answer

For case 1 :
u = 50 km/hr = $${{50 	imes 1000} \over {3600}}$$ m/s = $${{125} \over 9}$$ m/s, v = 0, s = 6 m, $$a$$ = ?
$$	herefore$$ 0
2
= u
2
+ 2$$a$$s
$$ \Rightarrow $$ $$a =  - {{{u^2}} \over {2s}}$$
$$ \Rightarrow $$  $$a =  - {{{{\left( {{{125} \over 9}} ight)}^2}} \over {2 	imes 6}}$$ = $$-$$16 m/s
2
For case 2 :
u = 100 km/hr = $${{100 	imes 1000} \over {3600}}$$ m/s = $${{250} \over 9}$$ m/s, v = 0, $$a$$ = $$-$$16, s = ?
$$	herefore$$ 0
2
= u
2
+ 2$$a$$s
$$ \Rightarrow $$ $$s =  - {{{u^2}} \over {2a}}$$
$$ \Rightarrow $$ $$s =  - {{{{\left( {{{250} \over 9}} ight)}^2}} \over {2 	imes -16}}$$ = 24 m

Answer

12 m

Answer

18 m

Answer

24 m

Answer

6 m

Motion in 1D

A car, moving with a speed of 50 km/hr, can be stopped by brakes after at least 6 m. If the same car is moving at a speed of 100 km/hr, the minimum stopping distance is

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