A device that does work with one movement and changes the size or direction of a force is a simple machine.
Answer:
Friction between the box and the floor is 25N to the left.
Explanation:
According to Newton's second law of motion, the net force acting on an object is equal to the produce between the object's mass and its acceleration:

where
m is the mass of the object
a is its acceleration
In this problem, we have two forces acting on the object:
- The applied force, F = 25 N, to the right
- The force of friction
, opposing the motion of the box, so to the left
So we can write the net force as

Also, we know that the box is moving at constant speed: this means its acceleration is zero, so

Therefore

WHich means:

And therefore,

which means that the force of friction is also 25 N.
Answer:
The ball experiences the greater momentum change
Explanation:
The momentum change of each object is given by:

where
m is the mass of the object
v is the final velocity
u is the initial velocity
Both objects have same mass m and same initial velocity u. So we have:
- For the ball, the final velocity is

Since it bounces back (so, opposite direction --> negative sign) with same speed (so, the magnitude of the final velocity is still u). So the change in momentum is

- For the clay, the final velocity is

since it sticks to the wall. So, the change in momentum is

So we see that the greater momentum change (in magnitude) is experienced by the ball.
Answer:
W = 650 [kJ]
Explanation:
The definition of work is denoted by the product of force by the distance traveled by the body, this distance traveled corresponds to the direction of the force.
In this case we have:
d = distance = 2.6[km] = 2600 [m]
F = force = 250 [N]
W = F*d = 250 * 2600 = 650000 [J] or 650 [kJ]