Question

1) A car is stopped for a traffic signal. When the light turns green, the car accelerates, increasing its speed from 0 to 4.90 m/s in 0.834 s. (a) What is the magnitude of the linear impulse experienced by a 74.0-kg passenger in the car during the time the car accelerates? (b) What is the magnitude of the average total force experienced by a 74.0-kg passenger in the car during the time the car accelerates?

2) A 67-kg fisherman in a 126-kg boat throws a package of mass m = 15 kg horizontally toward the right with a speed of v_i = 4.1 m/s. Neglecting water resistance, and assuming the boat is at rest before the package is thrown, find the velocity of the boat after the package is thrown.

Answer 1

(a) Find impulse:

Impulse = change in momentum

             = m ( delta V)

             = 74 kg ( 4.90 m/s )

             = 362.6 N

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Find acceleration,

            a = dV /dt = 4.90 / 0.834 = 5.875 m/s²

Force, F = ma = ( 74.0-kg ) ( 5.875 m/s² ) = 434.7 N