The driver of a three wheeler moving with a speed of 36 kmh-1 sees a c

1.	The driver of a three wheeler moving with a speed of 36 kmh-1 sees a child standing in the middle of the road and brings his vehicle to rest in 4.0 s just in time to save the child. What is the average retarding force on the vehicle? The mass of the three-wheeler is 400 kg and the mass of the driver is 65 kg.
Answer» Here u = 36 kmh^-1 = 36 x 5/18 = 10 ms^-1 v = 0; t = 4s and total mass = 400 + 65 = 465 kg As v = u + at, ⇒ 10 + 4a = 0 ⇒ a = -2.5 ms^-2 Retarding force = 465 x 2.5 = 1162.5 N

The driver of a three wheeler moving with a speed of 36 kmh-1 sees a child standing in the middle of the road and brings his vehicle to rest in 4.0 s just in time to save the child. What is the average retarding force on the vehicle? The mass of the three-wheeler is 400 kg and the mass of the driver is 65 kg.

Answer»

Here u = 36 kmh^-1 = 36 x 5/18 = 10 ms^-1

v = 0; t = 4s

and total mass = 400 + 65 = 465 kg

As v = u + at, ⇒ 10 + 4a = 0

⇒ a = -2.5 ms^-2

Retarding force = 465 x 2.5 = 1162.5 N