A disc with a mass of 1 kg moves horizontally to the right with a speed of 7 m/s on a table with negligible friction when it collides with a second disc with a mass of 9 kg. The second disc is moving horizontally to the right with a speed of 1 m/s at the moment of impact. The two discs stick together upon impact. What is the speed of the composite body immediately after the collision? (round your answer to the nearest tenth)

1.6 m/s

Explanation:

First you need to find the momentums of each disc by multiplying their velocities with mass.

disc 1: 7*1= 7 kg m/s

disc 2: 1*9= 9 kg m/s

Second, you need to find the total momentum of the system by adding the momentums of each sphere.

9+7= 16 kg m/s

Because momentum is conserved, this is equal to the momentum of the composite body.

Finally, to find the composite body's velocity, divide its total momentum by its mass. This is because mass*velocity=momentum

16/10=1.6

The velocity of the composite body is 1.6 m/s.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it