Question

1. you push back on the pavement and your skateboard goes forward - which of newtons 3 laws is this?
2. what is newtons 3rd law of motion?
3. a falling object accelerates until a force slows and stops its acceleration. what is this force called?
4. if you go from the earth to the moon which property changes - mass or weight?

Explanation:

1. When you push back on the pavement (action force), the pavement pushes you (and your skateboard) forward (reaction force). This is in line with Newton's 3rd law of motion.
2. Newton's 3rd law of motion states that for every action, there is an equal and opposite reaction.
3. When a falling object accelerates, air resistance (a type of frictional force) acts against the motion. As the object's speed increases, air resistance increases until it equals the force of gravity (for a falling object near the Earth's surface, the force due to gravity is \(F = mg\), where \(m\) is mass and \(g\) is the acceleration due to gravity). At this point, the net force is zero (\(F_{net}=F_{gravity}-F_{air - resistance}=0\)), and the object stops accelerating. This force is called air resistance (or drag).
4. Mass is a measure of the amount of matter in an object and is an intrinsic property. Weight is the force exerted on an object due to gravity (\(W = mg\)). Since the acceleration due to gravity (\(g\)) is different on the Moon (\(g_{Moon}\approx\frac{1}{6}g_{Earth}\)) compared to the Earth, the weight (\(W\)) of an object changes. The mass (\(m\)) remains the same because the amount of matter in the object does not change when moving from the Earth to the Moon.

Answer:

1. Newton's 3rd law
2. For every action, there is an equal and opposite reaction.
3. Air resistance (or drag)
4. Weight