Physics

posted by .

a 9.50-g bullet. moving horizontally with an initial speed vi , embeds itself in a 1.45-kg pendulum bob that is initially at rest. The length of the pendulum is L=0.745m. After the collision, the pendulum swings to one side and comes to rest when it has gained a vertical height of 12.4 cm. Find the initial speed of the bullet.

• Physics -

from the final height, the PE gained was

(m+M)gh (m is the bullet mass).

So the initial velocity of the bullet/block must be

1/2 (m+M)v^2=(m+M)gh or
V=sqrt(2gh)

Now the law of momentum conservation holds when the bullet hits the block

(m+M)V=mVi

(m+M)sqrt(2gh)=mVi

and solve for Vi

• Physics -

Thanx ,, but I got something equals to 239.51 m/s .. and I don't think it is right ..
I did it like this
1/2 ( 0.0095 + 1.45 ) sqrt ( 2*9.8*0.124) = 0.0095 vi

• Physics -

I got my mistake ,, thank you very much for the help :)

• Physics -

No I didn't get it right :S ,, I did it like this exactly
( 0.0095 + 1.45 ) sqrt ( 2*9.8*0.124) = 0.0095 vi

• Physics -

Thanks the answer was right, I related it to the small mass and it made sense ,, I submitted it , and it was right

• Physics -

239.51

• Physics -

239.51m/s

Similar Questions

1. physics

A ballistic pendulum, as shown in the figure, was a device used in the past century to measure the speed of bullets. The pendulum consists of a large block of wood suspended from long wires. Initially, the pendulum is at rest. The …
2. physics

A ballistic pendulum consists of a rectangular wooden block of mass 1.5 kg suspended from a ceiling. A bullet mass 0.025 kg undergoes a completely inelastic collision with the ballistic pendulum. Due to the collision the pendulum rises …
3. Physics

A ballistic pendulum was a device used in the past century to measure the speed of bullets. The pendulum consists of a large block of wood suspended from long wires. Initially, the pendulum is at rest. The bullet strikes the block …
4. Physics

A student performs a ballistic pendulum experiment using an apparatus similar to that shown in the figure. Initially the bullet is fired at the block while the block is at rest (at its lowest swing point). After the bullet hits the …
5. mambane

A 10.0g bullet is fired with a speed of 500m/s into a pendulum block of mass 5.00kg, suspended from a cord 0.600m long. Calculate: (a)the vertical height through which the pendulum rises. (b) the initial kinetic energy of the bullet. …
6. Physics

A 18 g bullet is fired into the bob of a ballistic pendulum of mass 1.4 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.
7. Physics

A 14 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. …
8. Physics

A 14 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. …
9. Physics- Ballistic pendulum

A simple pendulum is made from a 2 kg. block of wood suspended from a light cord of length 1 m. When the pendulum is hanging in such a way that it is stationary and vertical, a bullet is shot horizontally into the block of wood where …
10. Physics

A pendulum bob has a mass of 1kg. The length of the pendulum is 2m. The bob is pulled to one side to an angle of 10degree from the vertical. What is the velocity of the pendulum bob as it swings through it's lowest point?

More Similar Questions