Posted by esther on Wednesday, March 10, 2010 at 2:27pm.
A heavy wooden block rests on a flat table and a high-speed bullet is fired horizontally into the block, the bullet stopping in it. How far will the block slide before coming to a stop? The mass of the bullet is 10.5 g, the mass of the block is 10.5 kg the bulletís impact speed is 750 m/s, and the coefficient of kinetic friction between the block and the table is 0.220. (Assume that the bullet does not cause the block to spin.)
- physics - bobpursley, Wednesday, March 10, 2010 at 2:30pm
find the intial momentum of the block/bullet after impact, from that the velocity of the block. YOu now know that
solve for distance.
- physics - drwls, Wednesday, March 10, 2010 at 2:38pm
Once sliding begins, there is a friction force equal to
f = (M+m)*g*0.22 = 22.7 N
The initial speed V' of the block-with-bullet, after impact is given by the law of conservation of momentum:
m*750 = (M+m)V
V' = (.0105/10.51)*750 = 0.75 m/s
As a last step, equate the kinetic energy of the sliding block-plus-bullet to the work done against friction.
(1/2)(M+m)V'^2 = f X
and calculate the sliding distance X.
m and M are bullet and block mass, respectively.
- physics - esther, Wednesday, March 10, 2010 at 2:53pm
1/2 (10.5 kg) (750 m/s) + 1/2 (.0105 kg) (750 m/s) = .220 N * 10.5105 kg (9.81) distance
is this what i'm solving for?
- physics - esther, Wednesday, March 10, 2010 at 2:56pm
so the distance would be...... 2.96 m ?
- physics - drwls, Wednesday, March 10, 2010 at 5:24pm
No. You use the velocity V' AFTER collision (0.75 m/s), and you square it, as in the formula I wrote.
Your friction force f also looks wrong
Answer this Question
More Related Questions
- physics - A heavy wooden block rests on a flat table and a high-speed bullet is ...
- Physics - A heavy wooden block rests on a flat table and a high-speed bullet is ...
- physics - A block of wood with a mass of 1300g is sitting on a horizontal ...
- physics - suppose that a horizontal force of 0.7 n is required to pull a 5.0 kg ...
- Physics - A bullet of mass 15 g is fired with an initial speed of 287 m/s into a...
- Physics HELP! - A 20.0 g bullet is fired horizontally into a 85 g wooden block ...
- Physics- Elena please help! - A 20.0 g bullet is fired horizontally into a 85 g ...
- Physics - A 10 g bullet is fired into a 5 kg wooden block initially at rest on ...
- physics - A 11.0 g bullet is fired horizontally into a 108 g wooden block that ...
- physics - A bullet of mass 4.7 g is fired horizontally into a 2.4 kg wooden ...