A 0.1 kg arrow with an initial velocity of 30 m/s hits a 4.0 kg melon initially at rest on a friction-less surface. The arrow emerges out the other side of the melon with a speed of 20 m/s. What is the speed of the melon? Why would we normally not expect to see the melon move with the is speed after being hit by the arrow?​

Speed of the melon = 0.25 m/s

we would normally don't see the melon moving due to friction with the resting surface.

Explanation:

We use conservation of momentum:

Pi = Pf

with Pi = 0.1 kg * 30 m/s = 3 kg m/s

and Pf = 0.1 kg * 20 m/s + 4.0 kg * V = 2 kg m/s + 4 * V

Then using the equality above, we solve for V (velocity of the melon)

3 kg m/s = 2 kg m/s + 4 V

1 kg m/s = 4 kg * V

Then V = 1 / 4  M/s = 0.25 m/s

So we would normally don't see the melon moving due to friction with the resting surface.

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards

answer( sicar );