1. A 17 g bullet is fired into the bob of a ballistic pendulum of mass 1.6 kg. W

Question

1. A 17 g bullet is fired into the bob of a ballistic pendulum of mass 1.6 kg. When the bob is at its maximum height, the strings make an angle of 60° with the vertical. The length of the pendulum is 2.3 m. Find the speed of the bullet.

2. A 0.410-kg ball with a speed of 1.42 m/s rolls across a level surface toward an open 0.300-kg box that is resting on its side. The ball enters the box, and the box (with the ball inside it) then slides across the surface a distance of 0.563 m. What is the coefficient of kinetic friction between the box and the table?

The person here got it wrong so these are not the answers:

http://www.chegg.com/homework-help/questions-and-answers/copy-paste-img-url-url-bar-hard-time-seeing-image-q5591162

Please help, I need this as soon as possible. Thanks!

Explanation / Answer

given

mass of buullt m(1) = 17g = 17 * 10^-3kg

mass of pendulum m(2) = 1.6 kg

length of pendulum L = 2.3m

   angle ? = 60

this collision is completly ineleastic collssion

   m(1) v(b) + 0 =( m(1) + m(2)) v(f)

v(b) = ( m(1)+ m(2)/ m(1) ) * v(f)

the speed of v(f) immediatly after the collssion can be obtaind from the maximum height

v(f) = ?2gh(f)

where h(f) = L( 1-cos?)

then

   V(b) = ( m(1)+ m(2)/ m(1) ) *  ?2gL(1- cos?)

           =((0.017+1.6)/0.017) *sqrt(2*9.8 *2.3 *(1-cos(60)) m/s

= 451.58 m/s

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