Electric Motor Design

You and your friends want to have a contest designing your own electric toy cars. You will use the same basic idea in your design as the homemade electric motor below that includes a magnet, a metal screw, a battery, and an insulated wire: Select two of the following questions that you could investigate to ensure the most powerful motor for your toy car.

• How does the size of the battery affect the strength of the motor?

• How do the materials that the car is made from affect the speed of the car?

• How does the strength of the magnet affect the speed of the car?

• How does air resistance affect the strength of the motor?

• How does the size of the magnet affect the strength of the motor?

Based on the information to the left, what argument is best supported by the evidence presented?

• As the orbital period gets longer, the gravitational pull gets stronger.

• As the mass of the objects decrease, the gravitational pull gets stronger.

• As the mass of the objects increase, the gravitational pull gets stronger.

• As the distance between the objects increases, the gravitational pull gets stronger.

How can Jori investigate the relationship between the distance from the microwave and the strength of the electromagnetic field (EMF) when she makes popcorn?

• A. Jori can put an EMF meter inside the microwave after she pops the popcorn to take measurements.

• B. Jori can use an EMF meter at 5 cm away from different microwaves while they are being used.

• C. Jori can hold an EMF meter only at the distance she usually stands from the microwave and takes measurements while making popcorn.

• D. Jori can hold an EMF meter at different distances from the microwave while she is making popcorn and take measurements.

Based on the data in the table, what can be concluded about the relationship between mass and kinetic energy?

• A. The relationship between mass and kinetic energy is not proportional since the mass increases by different amounts for each object.

• B. The relationship between mass and kinetic energy is positive and proportional since the mass is 20 times the kinetic energy for each object.

• C. The relationship between mass and kinetic is negative and proportional since the kinetic energy is 1/20 of the mass for each object.

• D. There is no relationship between mass and kinetic energy because the mass and kinetic energy change by different amounts for each object.

Fill in the blank: The kinetic energy in Joules for a 4 kg ball at 4 m/s is ____.

• 16 J

• 32 J

• 64 J

• 8 J

Based on Graph 1: Sarah’s Data from the 2-kg Blue Ball, what is the kinetic energy when the velocity is 2 m/s?

• 2 J

• 4 J

• 8 J

• 16 J

Using Graph 1: Sarah’s Data from the 2-kg Blue Ball, which of the following velocities corresponds to a kinetic energy of 8 J?

• 1 m/s

• 2 m/s

• 3 m/s

• 4 m/s

Based on the pattern between mass and kinetic energy illustrated in Table 1, what is the missing data for the kinetic energy of a 4 kg ball at 4 m/s?

• 16 J

• 28 J

• 32 J

• 36 J

Based on this data, how would you describe the relationship between the mass and kinetic energy of an object?

• The kinetic energy is proportional to its mass.

• The kinetic energy doubles and mass stays the same.

• The kinetic energy increases at a faster rate than the mass.

• The kinetic energy increases by the same amount as the mass.

In which trial diagram is Sara exerting the most force on the bowling ball in order to achieve the increased speed?

• A. Sarah exerts the most force in Trial 1.

• B. Sarah exerts the most force in Trial 2.

• C. Sarah exerts the most force in Trial 3.

• D. Sarah exerts the same amount of force in all three trials.