Question

(a) 10 ms
(c) 18 m s-1
(b) 5 ms
(d) 1.8 ms
Ans. (b) 5 ms
Numericals
1. The speed of a car is 72 km h-! Express it in ms!
Ans. 20 m -
2. Express 15 m sin km -
Ans. 54 km -
3. Express each of the following in ml:
(a) 1 kmh (b) 18 km min-
Ans.(a) 0-278 m s' (b) 300 ms
1. Arrange the following speeds in increasing order
10 ml 1 km min. 18 km -​

Answer 1

Answer:

11th

Physics

Motion in a Straight Line

Stopping Distance and Reaction Time

A car is moving in a straig...

PHYSICS

A car is moving in a straight line with speed 18km h

−1

. It is stopped in 5s by applying the brakes. Find : (i) the speed of car in ms

−1

. (ii) the retardation and (iii) the speed of car after 2s of applying the brakes.

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ANSWER

Given, Speed=18km/h,t=5s

a)The speed of the car in m/s=18×

18

5

=5 m/s

b) The retardation is:

a=

t

v−u

=

5

0−5

=1m/s

2

c) The velocity of the as a funcition of time 2sis:

v(t)=5−t⇒v(t)=5−2=3m/s=10.8 km/h