A 60 kg from seal passenger, ridding in a car moving 40 MPH. is brought to rest

Question

A 60 kg from seal passenger, ridding in a car moving 40 MPH. is brought to rest by and air hag in a time of 4.0s. What impulse acts on the passenger? What average force is exerted on the passenger in the process? A playground merry-go-round with a 2.00m radius and 140 kg mass rotates about a frictionless vertical axle. A 25.0 kg child stands at a distance of 1.00m from the axle and the system (merry-go-round and child) rotates at the rate of 14.0 rev/min. the child then proceeds to walk to the edge of the merry-go-round. What is the angular speed of the system when the child reaches the edge?

Explanation / Answer

19.) v = 40 Mph = 40 x 1.609 = 64.36 km/h = 17.877777 m/s

Impulse = change in momentum = mv - mx 0 = mv = 60 x 17.8777777 = 1072.66667 kgm/s

Average force = Impulse / time = 1072.666667 / 4 = 268.166667 N

20.) Initial moment of inertial I = MR2/2 + mr2 = 140 x 22 /2 + 25x 12 = 305 kg m2

Final moment of inertial I' = MR2/2 + mr'2 = 140 x 22 /2 + 25x 22 =330 kgm2

According to the law of conservation of angular momentum, the angular momentum is always conserved as lond as there is no external torque.

So, I = I''

305 x 14 = 330 x '

' = 12.9393939 rev/min ~ 1.35 rad / sec

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