Plants
Energy
50
Light intensity, amount of carbon dioxide available and amount of water available affect _____?
rate of photosynthesis
50
What is wrong with the below answer?
"A moving toy car comes to a complete stop because some of the kinetic energy has been converted to heat and sound energy."
"A moving toy car comes to a complete stop because ALL of the kinetic energy has been converted to heat and sound energy."
Objects with any kinetic energy left means that it is still moving.
100
Explain why the graph becomes constant after a certain light intensity.
Either of the below:
1. Plant has received its maximum amount of carbon dioxide.
2. Plant has absorbed its maximum amount of water.
3. Chlorophyll has reached its maximum rate of photosynthesis.
100
The cart is released and it starts moving. What is wrong with the below description?
"The compressed spring exerts an outward pushing force on the cart, causing it to move."
(Elastic) potential energy in the compressed spring is converted to kinetic energy of the cart.
150
Describe 2 ways to collect data from this set up to draw a conclusion.
1. Volume of gas collected in the syringe after a certain amount of time
2. The number of bubbles produced by the plants within a certain amount of time.
150
In a wind-up toy, explain the relationship between the number of turns of the blades and the distance travelled by the toy car. 
As the number of turns of the blades increases, the rubber band becomes more twisted thus more (elastic) potential energy is stored in the rubber band. It is converted to more kinetic energy when the blades are released which increases the distance travelled by the toy car.
200
Explain the shape of the bottom 2 graphs.
(Y-axis: Rate of photosynthesis, X-axis: Light intensity)
Start: Same rate of photosynthesis as light intensity is the same for both setups, light intensity is the main factor.
End: Plant has absorbed maximum light intensity. Another factor (carbon dioxide or water) is the main factor affecting photosynthesis, ie. the 2 setups have different amounts of carbon dioxide or water available.
200
A pendulum is released from point 1. State the energy that the pendulum possesses through points 1-5. Then, state the energy conversion if the pendulum were to hit a wall at point 5.
Point 1: potential energy
Point 2: potential energy and kinetic energy
Point 3: kinetic energy
Point 4: potential energy and kinetic energy
Point 5: potential energy, which is converted to sound and heat energy upon hitting the wall.
300
Given that green coloured objects reflect green light, explain if green light is suitable to be used to grow plants.
Chlorophyll is a green pigment that reflects green light.
If only green light is given, no light can be absorbed by chlorophyll for photosynthesis. The plant cannot make food and energy to survive.
300
If the same cart is released on a rough surface vs a smooth surface, both starting with the same compressed spring, will they have the same speed at the moment of release? What about after 2 seconds?
Same speed at the moment of release as there is same amount of energy transfer from the compressed spring to the cart.
However due to more friction on the rough surface, more energy is converted to heat energy (instead of kinetic) as time passes. The cart on the rougher surface will have a slower speed.