1. An engineering team needs to design a system to stop a runaway cart on a track. Which modification is based on the principle of increasing friction?
- A. Streamlining the cart's body to significantly reduce its air resistance profile.
- B. Replacing the smooth track surface with a rougher material like gravel.
- C. Adding powerful magnets to the bottom of the cart and the track to cause repulsion.
- D. Installing a large sail on the cart to catch the wind and slow it down.
2. According to the Force-Velocity Model, what is the direct effect of increasing the force of friction acting on a moving object?
- A. It causes a greater rate of deceleration.
- B. It reduces the object's mass.
- C. It increases the object's forward momentum.
- D. It makes the contact surface smoother.
3. In the challenge of modifying a scenario to make a car stop safely, which two physical properties are identified as the key variables to manipulate?
- A. Velocity and time
- B. Mass and friction
- C. Color and temperature
- D. Gravity and air resistance
4. Which of the following correctly describes the cause-and-effect relationship when using a high-friction material to stop a car?
- A. Increased surface roughness → decreased friction → increased speed.
- B. Increased surface roughness → increased friction force → greater deceleration.
- C. Increased surface roughness → increased mass → greater deceleration.
- D. Increased surface roughness → decreased deceleration → longer stopping distance.
5. A student suggests that to stop a car more effectively, its mass should be significantly decreased. Why is increasing surface friction often a more direct and reliable strategy?
- A. Decreasing mass has absolutely no effect on how quickly an object can stop.
- B. Increasing friction creates a larger opposing force, which directly causes a greater change in velocity.
- C. Lighter cars are known to have braking systems that are fundamentally less efficient than those in heavier cars.
- D. The primary factor in stopping is air resistance, which is only increased by making the car larger, not lighter.