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

Initial velocity of the car (u) = $60km/hr^2$ = $16.67 m/s^2$

Final velocity (v) = 0 m/s

Time = 15s

________________________

Use this equation

v = u + at

0 = 16.67 + a(15)

15 a = -16.67

15 will shift

Divide it

a = $- 1.12 m/s^2$