Light and energy Flashcards
A safety vest is made of bright florescent colors and is lined with shiny strips in the front and at the back. Explain how the shiny strips help decrease the chance of a car hitting the person wearing it during night time or low light conditions.
More light is from the car headlights is reflected off the shiny strips into the drivers eyes, allowing the person to be seen at a greater distance away.
3 people of the same height stood at different positions between a light source and screen. The shadow of A was the largest followed by B, then C. Explain how the actors achieved this image.
A is standing the closest from the light source and would block the most light rays thus A has the biggest shadow.
C is the furthest to the light source and would block the least light rays thus C has the largest shadow
B is standing closer to the light source than C but further than A, and would block more light rays than C but less than A, thus the shadow is bigger than B but smaller than C.
A torch was shined at materials A, B , C, and D, and a data logger with a light sensor was behind the material. the experiment was conducted in a dark room. With A, the brightness of light (lux) recorded was 90, B 60, C 0, D 120.
Which material could be classified as opaque? Explain your answer.
Why should this experiment be conducted in a dark room?
Material C. No light was detected by the light sensor when material C was tested as it did not allow any light to pass through it to reach the light sensor. This shows that material C is an opaque material.
To ensure a fair test as no external light would affect the amount of light detected by the light sensor.
A person starts at the top of a slope and skated down. In term of forces and energy, explain why the skater comes to stop after some time.
As the skater moves, there is frictional force between the slope and the skate board, converting all the kinetic energy to thermal energy, slowing the skater down and comes to a stop.
A ball is loaded into a cannon were a spring is compressed and the ball is placed on it the spring is then released. The distance between point where the ball is first exits the cannon to the highest point of the ball is recorded.
How will the amount of kinetic energy that the possesses at point X change if a ball of different mass is used? Explain your answer.
You replace the original spring with spring W, of the same length. Spring W is stiffer and is harder to compress. When spring W is compressed to the same height as spring W, what will happen to the height of the ball when he uses spring W? Explain your answer.
The amount of kinetic energy is the same since the amount of elastic potential energy from the spring is the same.
The heights of the ball will increase as the spring possesses more elastic potential energy
