Need help, thank you! 1. A 3 kg object is moving to the right with a speed of 1

Question

Need help, thank you!

1. A 3 kg object is moving to the right with a speed of 1 m/s when it experiences

an impulse of 6 N s. What is the object’s velocity after the impulse?

2.A point mass m is moving at constant speed in a horizontal circular path of

radius r. What is the net work done on the mass after one complete revolution? Would this just be 0?

3. A tennis ball with mass 75 g is moving left at 25 m/s when it bounces against a wall

and rebounds with the same speed to the right.

       (a) (1 point) What net impulse did the wall give to the tennis ball?

       (b) (1 point) What net work did the wall do on the tennis ball to change its direction?

Explanation / Answer

1) Apply Impulse-momentum theorem

Impuse = change in momentum

-6 = m*(v2 - v1)

-6 = 3*(v2 - 1)

-2 = v2 - 1

v2 = -2+1

= -1 m/s

2) zero.

beacsue, Workdone = F*d*cos(90) (here 90 degrees is the agke between force and displacement)

= 0

3)

a) impulse = m*(v2 - v1)

= 75*10^-3*(25 - (-25))

= 3.75 N.s

b) net workdone = 0

since there is no change in kiectic energy of the ball.

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