Question

a toy is made up of a box with a plastic giraffe inside. the giraffe is attached to a spring. when the handle on the outside of the box is turned, the spring is compressed. a button then releases the spring and the giraffe pops out of the box. how is the law of conservation of energy represented in the action of the toy? f the giraffe always contains the same amount of potential energy or kinetic energy whether it is still or in motion. g the potential energy of the giraffe when not moving is added to the kinetic energy of the giraffe when it is moving. h the potential energy of the giraffe when the spring is compressed is transformed into kinetic energy when it moves. i the same amount of kinetic energy is created when the giraffe moves as is destroyed when the spring is compressed. hector conducts an investigation by stretching a rubber band across two nails 20 cm apart. he then uses a toy car to pull back on the rubber band and lets go of the car. maria determines the distance the car travels in 10 seconds. they then repeat the same steps but pull the rubber band back a little farther each time. which conclusion are hector and maria most likely to reach? a the heavier the car is, the farther it travels once it is let go. b the farther the rubber band is stretched, the greater the speed of the car. c the farther the car travels, the less the rubber band snaps back into place. d the greater the distance between the two nails, the more slowly the car travels.

Explanation:

Question 9

Step1: Analyze Option F

The giraffe does not always contain the same amount of potential or kinetic energy. When the spring is compressed, the potential energy (due to the spring's compression) is different from when it is moving (kinetic energy). So, Option F is incorrect.

Step2: Analyze Option G

The law of conservation of energy is about transformation, not addition in this sense. The total energy (potential + kinetic) is conserved, but it's a transformation, not a simple addition as described. So, Option G is incorrect.

Step3: Analyze Option H

When the spring is compressed, there is elastic potential energy. When the button is pressed and the giraffe pops out, this potential energy is transformed into kinetic energy (the energy of motion of the giraffe). This follows the law of conservation of energy (energy is transformed, not created or destroyed). So, Option H is correct.

Step4: Analyze Option I

Energy is not created or destroyed. Kinetic energy is not “created” when the giraffe moves. It is transformed from potential energy. So, Option I is incorrect.

Question 10

Step1: Analyze Option A

The experiment is about stretching the rubber - band, not about the mass (heaviness) of the car. There is no variable related to the car's mass in the described experiment. So, Option A is incorrect.

Step2: Analyze Option B

As the rubber - band is stretched farther, it has more elastic potential energy. When released, this potential energy is transformed into kinetic energy of the car. More potential energy (from more stretching) means more kinetic energy, and since \(v = \frac{d}{t}\) (and time \(t = 10\) seconds is constant in their experiment), a greater speed (as distance \(d\) will be larger for more stretched rubber - bands). So, Option B is correct.

Step3: Analyze Option C

The farther the car travels (if it has more speed due to more stretched rubber - band), the rubber - band actually has more potential energy initially (from more stretching) and snaps back with more “force” (but this is not the relationship they are testing. The key is the car's speed related to rubber - band stretch). So, Option C is incorrect.

Step4: Analyze Option D

The distance between the two nails is fixed at 20 cm initially, and they are stretching the rubber - band beyond that fixed distance. The variable is the stretch of the rubber - band (beyond the 20 cm between nails), not the distance between the nails. So, Option D is incorrect.

Answer:

1. H. The potential energy of the giraffe when the spring is compressed is transformed into kinetic energy when it moves.
2. B. The farther the rubber band is stretched, the greater the speed of the car.