I have tried to work this one out and really can't get it.

We have two carts that have magnets to keep them from touching. One cart is initially at rest and we push the second cart towards it. Because the two carts will not actually touch, the collision is elastic. Use the data given to find all the unknowns. Note that v1' is the velocity of cart 1 after the collision.
Mass 1: .51 kg
Mass 2: .50 kg
V1: 1.2 m/s
Unknowns are
V1'= ?
V2'= ?
P1= ?
P1'=?
% difference =?
KE1'= ?
KE2' = ?
% difference = ?

I hope you realize that v2 is zero.

You have two equations, two unknowns:
M1V1+M2V2=M1V1' + M2V2' solve that for V2' in terms of all the other.

1/2M1 V1^2+1/2 M2 V2^2=1/2 M1V1'^2 + 1/2 M2V2'^2
put the numbers you have for V2' into that, and start solving for V1'. Note: a bit of algebra is involved.

after you know V1',V2' the rest is easy.

Yea I do know about V2. And thanks so much, I really appreciate it!

To solve this problem, we can start by using the conservation of momentum and the conservation of kinetic energy.

1. Conservation of Momentum:
According to the conservation of momentum, the total momentum before the collision is equal to the total momentum after the collision. Mathematically, this can be represented as:
m1 * v1 + m2 * v2 = m1 * v1' + m2 * v2'
where:
m1 and m2 are the masses of carts 1 and 2, respectively
v1 and v2 are the initial velocities of carts 1 and 2, respectively
v1' and v2' are the final velocities of carts 1 and 2, respectively (unknowns)

2. Conservation of Kinetic Energy:
In an elastic collision, the total kinetic energy before the collision is equal to the total kinetic energy after the collision. Mathematically, this can be represented as:
(1/2) * m1 * v1^2 + (1/2) * m2 * v2^2 = (1/2) * m1 * v1'^2 + (1/2) * m2 * v2'^2
where:
m1, m2, v1, v2 are the same as before
v1'^2 and v2'^2 are the final velocities squared of carts 1 and 2, respectively (unknowns)

Now, let's substitute the given values and solve for the unknowns step by step:

Given:
m1 = 0.51 kg
m2 = 0.50 kg
v1 = 1.2 m/s

Step 1: Solving for v1'
Using the conservation of momentum equation, we can solve for v1':
0.51 kg * 1.2 m/s + 0.50 kg * v2 = 0.51 kg * v1' + 0.50 kg * v2'
v1' = (0.51 kg * 1.2 m/s + 0.50 kg * v2 - 0.50 kg * v2') / 0.51 kg

Step 2: Solving for v2'
Using the conservation of momentum equation, we can solve for v2':
0.51 kg * 1.2 m/s + 0.50 kg * v2 = 0.51 kg * v1' + 0.50 kg * v2'
v2' = (0.51 kg * 1.2 m/s + 0.50 kg * v2 - 0.51 kg * v1') / 0.50 kg

Step 3: Solving for P1
P1 represents the initial momentum of cart 1:
P1 = m1 * v1

Step 4: Solving for P1'
P1' represents the final momentum of cart 1:
P1' = m1 * v1'

Step 5: Solving for the percentage difference
The percentage difference can be calculated using the formula:
% difference = (P1' - P1) / P1 * 100

Step 6: Solving for KE1'
The final kinetic energy of cart 1 can be calculated using the formula:
KE1' = (1/2) * m1 * v1'^2

Step 7: Solving for KE2'
The final kinetic energy of cart 2 can be calculated using the formula:
KE2' = (1/2) * m2 * v2'^2

Step 8: Solving for the percentage difference
The percentage difference in kinetic energy can be calculated using the formula:
% difference = (KE2' - KE1') / KE1' * 100

By substituting the values and solving these equations, you will be able to find all the unknowns in the given scenario.