A friend pushes a sled across horizontal snow and when it gets up to speed the friend jumps on. After the friend jumps on, the sled gradually slows down. Which forces act on the combined sled plus friend after the friend jumps on

      v’ =(  )  v

we see that the greater the difference, the more the sled slows down.

friction force

Explanation:

When the man pushes the sled he does work and the sled acquires a speed and as long as it is supplied with an energy equal to the work of the chipping force with the snow, the speed is maintained.

When he jumps on the sled, a collision occurs and the initial moment

             p₀ = mv

is increased by the increase in mass

             m_f= (m + M_{man} ) v '

In this case there is no longer any external force applied and the only external force is friction, which causes the sled to stop, even when it is small, but the significant reduction in speed is due to the increase in masses.

            p₀ = p_f

            mv = (m + M_{man}) v '

            v ’=   v

            v’ =(  )  v

Therefore, we see that the greater the difference, the more the sled slows down.

The only forces that act on the sled with the man are the friction that is responsible for the decrease in speed and weight with the normal

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.