1. a. What is a force?
Answer: A force is a cause of motion or a change in motion.
b. Imagine that your bike is covered with dried-on mud. You are about to use a garden hose to wash off the mud. How could you wash the bike the fastest?
Answer: You could wash the bike fastest by turning on the water full force.
c. Using your understanding of forces, explain how a team can win a tug-of-war.
Answer: The team that applies the greatest amount of force on the rope will win the tug-of-war.
d. Describe how you might apply a force to stop a moving object.
Answer: Answers will vary, but possible examples may include playing a racquet sport, catching a ball, or braking on a bike or in a car.
2. You have been asked to design ramps for two problems. For each problem, explain what you need to think about, and what the ramp would look like. You can draw a design with labels to help with your description.
a. A student in a wheelchair is on a stage that is 2 m above the floor. The student needs to move safely from the stage to the floor.
Answer: The ramp should not be steep. The wheelchair could move too quickly on a steep ramp. The student would not be safe. The ramp could have switchbacks if space was a problem.
b. Several boxes are in a room on the second floor of an apartment building. The boxes need to get to the ground quickly and safely.
Answer: The ramp should be steep. The boxes need to move along it quickly. Do not make it so steep that the boxes “free fall” to the ground.
Note: Students may have drawn illustrations to assist their explanations.
3. a. Many things were powered with a cranking mechanism in the “old days.” Using cranks is unusual today. Why do you think cranks are not used often any more?
Answer: Most modern devices use electricity, batteries, or gas to power them. It takes less effort than using a crank or winding mechanism. Crank mechanisms were dangerous in cars.
b. Devices today usually use electricity, batteries, or gas to give them power. What is an advantage of using a crank or wind-up mechanism instead?
Answer: A crank mechanism uses the power of the person cranking it. This power is a “renewable resource.” After a little rest, the person can continue cranking. Electricity, batteries, and gas all are resources that cost money.
Two activities were offered as Optional Follow-up Activities. There is no mark assigned. However, students may choose to send in one of these activities with their assignment. If they take this initiative, it would be helpful if you could provide feedback and an acknowledgement of the extra work done.
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