Question

Brakes are applied to a car travelling at 30m/s. Its velocity is reduced to 20m/s in 5sec.Calculate the retardation produced by the brakes.Also calculate distance covered in 5 sec?

Answer 1

Explanation:

Initial velocity, u=18 km/h

u=18×

3600

1000

=

3600

18000

m/s=5m/s

Final velocity, v=0 m/s

Time, t=2.5 sec

Acceleration, a=?

Using, v=u+at

a=

t

v−u

=

2.5

0.5

=−2m/s

2

So, retardation is 2m/s

2

so it can travel 4km in 5secs

Answer 2

Answer:

What is retardation?

• Disability is often used to describe problems in human intellectual development that result in a lack of intelligence or other types of physical or learning disabilities.
• Delay can also indicate when something is being prevented from growing or fully developing.

What is velocity?

• velocity is the directional velocity of a moving object as an indication of its rate of change of position as observed from a specific frame of reference and measured with a specific time standard.

Explanation:

given:- u=30m/s

            v=20m/s

            t=5sec

to find:-distance(d)=?

formula:- (1) v= u + at

               (2) s = ut + 1/2 at^2

solution:- v = u + at

               a = v - u/t

               a = 20-30ms^-1/5s

                a = -2 ms^2

               s = ut + 1/2 at^2

               s = 30*5 - 1/2 *2*25

                 s = 125m

Distance covered in 5 second is 125m.

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