Well, if your question is how light affects plants,
then you would want to design an experiment that plays aruond with the amount of light a plant gets
thus the thing changing (or variable) would be amount of light
When you throw the ball in the air it is considered kinetic energy. Once the ball reaches its max height, it stops moving and all kinetic energy turns into potential energy. So when the ball is at its highest point.
Answer:
I think they use it at night because they want to avoid involving themselves in road accident while crossing the street. When there are reflective strips on their clothes, drivers do notice them even at far ends of the street since the strips will reflect the rays from the car lights to the driver,hence, the driver notifies that there is a pedestrian crossing and therefore slows down.
Answer:
d)energy
Explanation:
Waves can transfer energy over distance without moving matter the entire distance. For example, an ocean wave can travel many kilometers without the water itself moving many kilometers. The water moves up and down—a motion known as a disturbance. It is the disturbance that travels in a wave, transferring energy.
Answer: 
Explanation:
The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

Q = Heat absorbed=
Joules
m= mass of copper = 454 g
c = specific heat capacity = 
Initial temperature of the copper =
= 23.0°C
Final temperature of the water =
= ?
Change in temperature ,
Putting in the values, we get:


The final temperature of copper will be 