7) 2,197 kg
The weight of an object on Earth is given by:
where m is the mass of the object and is the acceleration due to gravity. Since we know the weight of the object, W=21,532 N, we can re-arrange the equation to calculate the object's mass:
8) 2,197 kg
Mass is an intrinsec property of an object: it says "how much matter" is contained within an object. Therefore, the mass of an object does not depend on its location: so, the object has the same mass on Earth and on the moon, and so its mass is still the same as the previous exercise, 2,197 kg.
9) 187,500 N
The force exerted on an object is given by Newton's second law:
where m is the mass of the object and a its acceleration. In this problem, and
, so the force exerted on the object is
10) 2nd Law
Newton's second law states that an object which is acted upon a force experiences an acceleration given by:
where F is the force and m the mass of the object. As a result, the object accelerates, so if it was at rest, it starts moving.
This is exactly what happens in this example: the ball is initially at rest, but then a force is applied on it (by the kick), so the ball is accelerated and it starts moving.