A 55-kg skater moving at 2.5 m/s overtakes a 45-kg skater moving at 1.0 m/s in the same direction and collides with her. The two skaters stick together. What is their final speed?

1.825m/s

Explanation:

Using the law of conservation of momentum which says that momentum before collision is equal to sum of momentum after collision.

m1u1+m2u2 = (m1+m2)v

m1 and m2 are the masses

u1 and u2 are the initial velocities

v is final velocity of the two bodies after collision

Substitute the given parameters into the formula

55(2.5)+45(1) = (55+45)v

137.5+45 = 100v

182.5 = 100v

v = 182.5/100

v = 1.825m/s

Hence their final speed is 1.825m/s

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