Question

A car traveling at 25.0 m/s applies the brakes and decelerates uniformly at a rate of 1.2 m/s2 .
(a) How far does it travel in 3.0 s?
(b) What is its velocity at the end of this time interval?
(c) How long does it take for the car to come to a stop?
(d) What distance does the car travel before coming to a stop?

Answer 1

Answer:

(a) 69.6 m

(b) 21.4 m/s

(c) 21 s approx.

(d) 139 m approx.

Step-by-step explanation:

(a) s = ut+1/2at^2

u = 25 m/s

t = 3 s

a = 1-.2 m/s^2

s = 25*3+1/2*-1.2*3*3

s = 69.6 m

(b) v = u+at

v = 25+(-1.2)*3

v = 25-3.6

v = 21.4 m/s

(c) v = u+at

0 = 25+(-1.2)*t

Transpose 25 to the other side,

25 = 1.2t

20.83 s = t

Approx. 21 s

(d) s = ut+1/2at^2

s = 25*21+1/2*-1.2*21*21

525-276.6

139.4 m