# Physics momentum problem -- Collision between 2 blocks that stick together

• Inwoodspaki
In summary, momentum in physics is a measurement of an object's motion and difficulty to stop, calculated by multiplying its mass and velocity. A collision is when two or more objects come into contact, which can be elastic or inelastic. The law of conservation of momentum states that in a collision, the total momentum before and after remains constant. After a collision, the combined momentum of two objects is the sum of their individual momentums. The coefficient of restitution measures the elasticity of a collision, with a higher value indicating a more elastic collision and a lower value indicating a more inelastic collision. A coefficient of restitution of 0 means a completely inelastic collision.
Inwoodspaki
Homework Statement
A small cube, with a mass of 25 g, slides along a frictionless horizontal surface at a constant speed of 18 m/s until it collides with, and sticks to, a large wooden 3.5 kg block. The large block is attached to the left end of a spring with a spring constant of 100 N/m as shown above.

a. What is the momentum of the cube before the collision?
b. What is the kinetic energy of the cube before the collision?
c. *Find the speed of the combined cube and block system just after the collision.
d. *Find the kinetic energy of the cube-block system just after the collision.
e. *What is the maximum potential energy that can be stored in the spring due to this collision?
f. *How far will the cube-block system move before it stops?
Relevant Equations
KE = 1/2 mv^2
P= mv

maybe D = (KE) / (m)(g) ?
So far I found the answer for a and b, but when I attempted to do the other ones I was completely lost.

A.) P= MV
M = 25g = .025kg
V = 18

.025 * 18 = .45kg*m/s

B.) KE= 1/2 mv^2
1/2 (.025)(18)^2
4.05 J

For c) what general principle of mechanics might be relevant? Hint: you're looking for something that is conserved throughout the collision.

In case this is what is blocking you...
You should consider the collision process as taking negligible time. This means that the spring has only a negligible effect during it, so you ignore the spring when answering c.

## 1. What is momentum in physics?

Momentum is a physical quantity that describes the motion of an object. It is the product of an object's mass and velocity, and is a measure of how difficult it is to stop the object's motion.

## 2. How is momentum conserved in a collision?

In a collision between two objects, the total momentum before the collision is equal to the total momentum after the collision. This is known as the law of conservation of momentum.

## 3. What happens to the momentum of two objects that stick together after a collision?

If two objects stick together after a collision, their momenta are combined into a single, larger momentum. This is because the total mass of the two objects is now greater, and the combined velocity is lower than the individual velocities before the collision.

## 4. How can you calculate the final velocity of two objects that stick together after a collision?

To calculate the final velocity of two objects that stick together after a collision, you can use the law of conservation of momentum. Set the initial momentum of the two objects equal to the final momentum of the combined object, and solve for the final velocity.

## 5. Is momentum always conserved in a collision?

In an ideal, perfectly elastic collision, momentum is always conserved. However, in real-world collisions, some energy may be lost as heat or sound, causing a slight decrease in the total momentum. This is known as an inelastic collision.

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