Question

A car of mass 1000kg moving at a speed of 80km per h-1 is brought to rest in 20s by a costant retarding force find the: (a) retardation and (b) retarding force exerted on the car.​

Answer 1

Answer:

The formula for retardation is a=v-u/t

Force=Mxa

Answer 2

Answer :

• Retardation = -11.11 m/s² or 11 m/s² (approx)

• Retarding Force = - 11, 000 N

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Given :

Mass of the car = 1000 kg

Initial Speed Of Car = 80 km/h = 22.22 m/s

Final Velocity Of Car = 0 ( as it comes to rest )

Time = 20 seconds

To Find :

a) Retardation

b) Retarding force exerted on the car

Sølution :

Here , acceleration is considered negative i.e. Retardation .

• Formula used : $\Large\bold{\boxed{\sf{\red{v\:=\:u\:+\:at}}}}$

=> 0 = 22.22 + a(20)

=> - 20a = 22.22

=> a = $\sf\:-\: \dfrac{22.22}{20}$

=> a = - 11.11 m/s² ( -ve sign shows retardation )

Retardation = - 11.11 m/s² or - 11 m/s² (approx)

• Formula used : $\Large\bold{\boxed{\sf{\red{F\:=\:ma}}}}$

=> F = 1000(-11)

=> F = - 11, 000 N (-ve sign shows retarding force )

⠀Retarding Force = - 11, 000 N

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