Question

1. describe when a student rides a skateboard on a level surface, newtons three laws of motion act simultaneously. which statement accurately describes how one of newtons laws of motion applies to the skateboarder? teks 8.7b

a newtons third law of motion states that when the skateboarder pushes on the ground, the ground pushes back on the skateboarder.
b newtons second law of motion states that the acceleration of the skateboarder decreases as the net force increases.
c newtons first law states that the skateboarder accelerates because the forces on the skateboarder are balanced.
d newtons second law of motion states that there is a net force on the skateboarder when they move at constant speed.

1. analyze a system consists of an air hockey table, puck, and the air flow from the table. the puck hovers on the air until it is hit. then the puck accelerates. when the puck collides with the side of the table, it changes direction.

all three of newtons laws of motion act simultaneously within this system. when does newtons first law of motion apply to the hockey puck? teks 8.7b
a when the puck speeds up after it is hit
b when the puck changes direction
c when the puck hovers on the air before it is hit
d when the puck collides with the table and the table exerts a force on the puck

Explanation:

1. For question 3:

• Newton's third - law states that for every action, there is an equal and opposite reaction. When the skateboarder pushes on the ground (action force), the ground pushes back on the skateboarder (reaction force), which is option A.
• Option B is incorrect because Newton's second law states that acceleration is directly proportional to the net - force ($F = ma$), so acceleration increases as the net force increases.
• Option C is incorrect because Newton's first law states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. A skateboarder accelerates when there is an unbalanced force, not when forces are balanced.
• Option D is incorrect because when a skateboarder moves at a constant speed, the net force on them is zero according to Newton's first law, not Newton's second law.

1. For question 4:

• Newton's first law (the law of inertia) states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. When the puck hovers on the air before it is hit, it is either at rest or moving with a constant velocity (assuming no air resistance or other external forces), so Newton's first law applies.
• Option A (when the puck speeds up after it is hit) is an example of Newton's second law ($F = ma$) as a force causes a change in velocity (acceleration).
• Option B (when the puck changes direction) is also an example of Newton's second law as a force causes a change in the direction of velocity (acceleration).
• Option D (when the puck collides with the table and the table exerts a force on the puck) is an example of Newton's third law (action - reaction pair).

Answer:

1. A. Newton's third law of motion states that when the skateboarder pushes on the ground, the ground pushes back on the skateboarder.
2. C. when the puck hovers on the air before it is hit