Question

when a car travel at a speed of 60km/he applies brake it comes to rest in 15s then the retardation of the car is​

Answer 1

Given

• a car travel at a speed of 60 km/h applies brake it comes to rest in 15 s

To Find

• Retardation of the car

Concept Used

• Retardation and acceleration are both same but opposite in direction

Solution

Initial velocity , u = 60 km/h = 16.67 m/s²

Final velocity , v = 0 m/s

Since , finally comes to rest

Time , t = 15 s

Acceleration , a = ? m/s²

Apply 1st equation of motion ,

⇒ v = u + at

⇒ (0) = (16.67) + a(15)

⇒ 15a = -16.67

⇒ a = -1.12 m/s² 

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Answer 2

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When a car travel at a speed of 60km/he applies brake it comes to rest in 15s then the retardation of the car is.

Formula used here:

a =(v+u)/2×t

v=u+at

Method to do:

Just by converting the initial velocity in meter per second and apply the formula to find out the actual result .

Additional inf:

Retardation-It refers to the negative form of accleration means when the moving object or body covers any distance in opposite direction from the target.

Solution:-

Using formula,

v= u +at

Then,

initial velocity=60km/hrs

=(60x1000)/60x60

= 16.67 m/s

Final velocity=0m/s

Time taken =15 seconds

So,

v=u+at

0=16.67+15a

a= -16.67/15m/s²

a= -1.11m/s²

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