Question

26.
A car is decelerating uniformly, its velocity changing from 30
ms to 15 ms in 75 m. How much further will it travel before
coming to rest?
(a) 25 m
(b) 50 m
(c) 75 m
(d) 100 m

Answer 1

Answer:

100 m

Explanation:

Initial velocity 'u'= 30m/s

Final velocity 'v'= 15m/s

Distance 's'= 75m

Now using equation of motion,

v²-u²= 2as

15²-30²= 2x75a

225-900= 150a

-675=150a

a= -4.5 m/s²

Now,

u= 30m/s

v= 0 (Body will come at rest)

a= -4.5m/s²

v²-u²=2as

0²-30²=2x-4.5s

-900=-9s

s=100m

Car will travel 100 metre more before coming to rest

Answer 2

Answer:

a) 25 m

Explanation:

2 a S = vf^2 - vi^2

a = vf^2 - vi^2 /2 S

a = ( 15 )^2 - ( 30 )^2 / 2 ( 75)

a = -4.5 ms-2

S = vf^2 - vi^2 / 2 a

S = ( 0 )^2 - ( 15 )^2 / 2 ( -4.5)

S = 25 m