Question

alisa, a skateboarder, is riding down a hill. if alisa and the skateboard are considered a single object, what forces are acting on her? choose the three correct answers
checkbox friction
checkbox normal force
checkbox gravity
checkbox push
checkbox tension

Explanation:

1. Friction: When Alisa skates down the hill, the skateboard and the hill's surface interact, so friction (a contact force opposing motion) acts.
2. Normal Force: The hill's surface exerts a normal force (perpendicular to the surface) on the skateboard - Alisa system, as they are in contact with the hill.
3. Gravity: Gravity is a non - contact force that pulls the system (Alisa + skateboard) towards the center of the Earth, causing the motion down the hill.

• "Push" is incorrect as there's no external push force here. "Tension" is incorrect as there's no tension - producing element (like a rope) in this scenario.

Answer:

• Friction
• Normal force
• Gravity