13. to answer this question, refer to he roller coaster design\ passage and figures.
the students assume total mechanical energy is conserved in their model. which of the following statements best explains the law of conservation of energy as demonstrated by the roller coaster car?
a. the total kinetic energy of the car remains constant at all points.
b. the cars potential energy is created as it moves to lower points on the track.
c. as the car moves, potential energy is transformed into kinetic energy, and vice versa, keeping the total mechanical energy constant.
d. the energy lost due to friction is converted into useful mechanical energy, increasing the cars speed.
14. to answer this question, refer to he roller coaster design\ passage and figures.
if the students wanted to investigate how the mass of the roller coaster car affects its speed at point d, how could they design an experiment to determine the effect of the mass?
a. use different starting heights for coaster cars of different mass and measure its speed at point d.
b. vary the type of track material used, keeping the mass and starting height constant and measure the speed of the car at point d.
c. use coaster cars with different masses, keeping the initial height at point a constant, and measure the speed of each car at point d.
d. measure the kinetic energy of the car at point d for one mass, then calculate the potential energy at point a.
15. which sequence of energy transformations occurs after a battery - operated flashlight is turned on?
a. electrical → light → chemical
b. electrical → chemical → light
c. chemical → light → electrical
d. chemical → electrical → light

Question

13. to answer this question, refer to 	he roller coaster design\ passage and figures.
the students assume total mechanical energy is conserved in their model. which of the following statements best explains the law of conservation of energy as demonstrated by the roller coaster car?
a. the total kinetic energy of the car remains constant at all points.
b. the cars potential energy is created as it moves to lower points on the track.
c. as the car moves, potential energy is transformed into kinetic energy, and vice versa, keeping the total mechanical energy constant.
d. the energy lost due to friction is converted into useful mechanical energy, increasing the cars speed.
14. to answer this question, refer to 	he roller coaster design\ passage and figures.
if the students wanted to investigate how the mass of the roller coaster car affects its speed at point d, how could they design an experiment to determine the effect of the mass?
a. use different starting heights for coaster cars of different mass and measure its speed at point d.
b. vary the type of track material used, keeping the mass and starting height constant and measure the speed of the car at point d.
c. use coaster cars with different masses, keeping the initial height at point a constant, and measure the speed of each car at point d.
d. measure the kinetic energy of the car at point d for one mass, then calculate the potential energy at point a.
15. which sequence of energy transformations occurs after a battery - operated flashlight is turned on?
a. electrical → light → chemical
b. electrical → chemical → light
c. chemical → light → electrical
d. chemical → electrical → light

Accepted Answer

# Brief Explanations:
13. The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed. In a roller - coaster model with conserved total mechanical energy, potential energy ($PE = mgh$) and kinetic energy ($KE=\frac{1}{2}mv^{2}$) are transformed into each other.
   - Option A: Kinetic energy changes as the car's speed changes (e.g., at different heights), so it is incorrect.
   - Option B: Potential energy ($PE = mgh$) decreases as the height $h$ decreases (when moving to lower points), and it is not created. This option is incorrect.
   - Option C: As the car moves down, $h$ (for potential energy) decreases and speed $v$ (for kinetic energy) increases (potential to kinetic), and as it moves up, $h$ increases and $v$ decreases (kinetic to potential), keeping the total mechanical energy ($E = KE+PE$) constant. This option is correct.
   - Option D: Energy lost due to friction is usually dissipated as heat (not converted into useful mechanical energy to increase speed). This option is incorrect.
14. In an experiment to find the effect of mass on speed at Point D, we use the control - variable method.
   - Option A: Using different starting heights introduces another variable (height, related to potential energy), so we cannot isolate the effect of mass. This option is incorrect.
   - Option B: Varying track material (introduces friction as a variable) while keeping mass and height constant does not help in studying the effect of mass. This option is incorrect.
   - Option C: By keeping the initial height (so initial potential energy $PE = mgh$, where $h$ is constant) constant and changing mass, we can observe the effect of mass on speed (related to kinetic energy $KE=\frac{1}{2}mv^{2}$) at Point D. This option is correct.
   - Option D: Measuring kinetic energy for one mass and calculating potential energy does not show the effect of mass variation. This option is incorrect.
15. For a battery - operated flashlight:
   - Batteries store chemical energy. When the flashlight is turned on, the chemical energy in the battery is converted into electrical energy (to power the circuit).
   - The electrical energy is then converted into light energy (by the bulb). So the energy transformation sequence is chemical$\to$electrical$\to$light.

# Answer:
13. C. As the car moves, potential energy is transformed into kinetic energy, and vice versa, keeping the total mechanical energy constant.
14. C. Use coaster cars with different masses, keeping the initial height at Point A constant, and measure the speed of each car at Point D.
15. D. chemical $\to$ electrical $\to$ light

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Answer: