Question

please answer fast
when brakes applied

see pic ​

Answer 1

QUESTION :

a car travels with a uniform velocity 50 m/s for 10 seconds. The brakes are applied and the car is uniformly retarded and comes to rest in further 10 seconds. find

1. the retardation
2. the distance which the car travels after applying brakes.

ANSWER:

1.) Retardation = 5 m/s²

.................................

2.) distance travelled after applying brakes = 250 meter

____________________

Explanation:

given that,

a car travels with a uniform velocity 50 m/s for 10 seconds.

here,

we have,

initial velocity of car = 50 m/s

also,

given that,

The brakes are applied and the car is uniformly retarded and comes to rest in further 10 seconds.

here we have,

final velocity of the car = 0 m/s [car stops]

time for decelerating = 10 seconds

now,

To find:

1.) Retardation:

we have,

initial velocity(u) = 50 m/s

final velocity(v) = 0 m/s

time take(t) = 10 s

by

the equation of motion

v = u + at

where,

a = acceleration

putting the values,

0 = 50 + a(10)

10a + 50 = 0

10a = -50

a = -50/10

a = -5 m/s²

negation of acceleration shows the retardation

so,

Retardation = 5 m/s²

now,

2.)The distance which the car travels after applying brakes.

here,

we have,

initial velocity(u) = 50 m/s

final velocity(v) = 0 m/s

Acceleration(a) = -5 m/s²

by the equation of motion,

v² = u² + 2as

where,

s = distance travelled after applying brakes,

putting the values,

(0)² = (50)² + 2(-5)s

-10s + 2500 = 0

-10s = -2500

s = -2500/-10

s = 250 m

so,

distance travelled after applying brakes

= 250 meter