# Physics

posted by .

A bullet with a mass of 55 grams moving with a speed of 100 m/s slams into and wedges in a 1.9 kilogram block of wood supported by a string initially at rest. Which one, conservation of energy or conservation of momentum, can be applied to this situation? Why?

I think it's conservation of momentum because kinetic energy is not conserved in inelastic collisions. Correct?

• Physics -

Also, how high does the block swing after being hit by the bullet?

• Physics -

Actually, you can use the conservation of momentum first to find the initial velocity of the bullet-block system, and then you can plug that velocity into 1/2mv^2=mgh and solve for the height that the block swings, which gives a value of 0.403 m.

Correct?

• Physics -

Yes, that is exactly how to do the problem.

You are also correct that mechanical energy is not conserved.

• Physics -

Eureka!

## Respond to this Question

 First Name School Subject Your Answer

## Similar Questions

1. ### physics

A gun is fired vertically into a 1.55 kg block of wood at rest directly above it. If the bullet has a mass of 21.0 g and a speed of 190 m/s, how high will the block rise into the air after the bullet becomes embedded in it?
2. ### Physics - URGENT

A small block of mass 5 kg initially rests on a track at the bottom of a circular, vertical loop-the-loop, which has a radius of 0.8 m. The surface contact between the block and the loop is frictionless. A bullet of mass 0.7 kg strikes …
3. ### Physics

A block of wood of mass 0.91 kg is initially at rest. A bullet of mass 0.047 kg traveling at 104.7 m/s strikes the block and becomes embedded in it. With what speed do the block of wood and the bullet move just after the collision?
4. ### Physics

A bullet with a mass of 0.01kg is fired horizontally into a block of wood hanging on a string. The bullet sticks in the wood and causes it to swing upward to a height of 0.1m If the mass of the wood block is 2kg, what is the initial …
5. ### Physics

A 10 kilogram block initially hangs at rest at the end of two 10 meter strings of negligible mass as shown on the left diagram above. A 0.009 kilogram bullet, moving horizontally with a speed of 1600 meters per second, strikes the …
6. ### physics

A bullet with mass m = 5.21 g is moving horizontally with a speed v=367 m/s when it strikes a block of hardened steel with mass M = 14.8 kg(initially at rest). The bullet bounces o the block in a perfectly elastic collision. (a) What …
7. ### Momentum

A 4.4 g bullet is fired into a block of wood with a mass of 21.3 g. The wood block is initially at rest on a 1.3 m tall post. After the collision, the wood block and bullet land 2.4 m from the base of the post. Find the initial speed …
8. ### Physics

A bullet of mass 10.6 grams is fired with a speed of 125 meters per second toward a wood block of mass 187 grams initially at rest on a very smooth (assume frictionless) surface. What is the change in momentum of the bullet if it becomes …
9. ### physics

As shown in the diagram, a bullet of mass 7.0 g strikes a block of wood of mass 2.1 kg. The block of wood is suspended by a string of length 2.0 m, forming a pendulum. The bullet lodges in the wood, and together they swing upward a …
10. ### Physics

A 15.0 gram bullet with a speed of v is fired into a 400 gram block of wood that is initially at rest on a surface. The coefficient of kinetic friction between the block and the surface is 0.250. The block of wood is attached to a …

More Similar Questions