Balanced Forces
What is the unit of force?
A Newton
What is the term for the force that opposes motion between two surfaces in contact?
Friction
Does weight change if you go to the Moon?
Yes, weight is less on the Moon because the Moon’s gravity is weaker than Earth’s.
What is the closest planet to the Sun?
Mercury
What is the purpose of writing an aim in a scientific study?
To clearly state the main purpose or goal of the experiment, describing what the study intends to investigate.
A ball is rolling at a constant speed in a straight line. Are the forces on it balanced or unbalanced? Why?
Balanced, because the ball's motion does not change, meaning the forces acting on it are equal.
Name one example of a contact force and one example of a non-contact force.
Contact force: Friction.
Non-contact force: Gravity.
What is the formula to calculate weight?
Weight = Mass × Gravitational acceleration (W = m x g)
What is the main reason we see phases of the Moon?
The phases occur because of the changing angles of sunlight illuminating the Moon as it orbits Earth.
How does a hypothesis differ from an aim in a scientific study?
A hypothesis is a testable prediction about the outcome of the experiment, while an aim is a statement of what the study seeks to accomplish.
If a book is sitting still on a table, what can you say about the forces acting on it?
They are balanced (gravity and the normal force are equal and opposite).
What type of force causes a parachute to slow down a falling skydiver?
Air resistance, which is a contact force.
Air resistance is a contact force because it involves physical interaction between the object and air particles.
Name two examples of simple machines used in everyday life. Include the simple machine description in your answer
A pair of scissors (lever and wedge) and a ramp (inclined plane).
What is the difference between a solar eclipse and a lunar eclipse?
Identify the independent variable in an experiment where students test the effect of different amounts of sunlight on plant growth.
Independent variable: Amounts of sunlight
Dependent variable would be plant growth
What happens to an object’s motion if the forces acting on it are unbalanced?
The object will accelerate in the direction of the greater force.
The Moon stays in orbit around Earth. What non-contact force is responsible for this?
Gravity
A lever has a fulcrum placed in the center. If the load on one side is 50 N, how much force is needed on the other side to balance it if the distances from the fulcrum are equal?
50N. Since the distances are equal, the forces must be equal to balance the lever.
Why does the Southern Hemisphere experience summer when the Northern Hemisphere experiences winter?
This happens because Earth's axis is tilted. When the Southern Hemisphere is tilted toward the Sun, it receives more direct sunlight, causing summer, while the Northern Hemisphere receives less sunlight, causing winter.
Why is it important to control variables in a scientific study, and what is a controlled variable?
Controlling variables is important to ensure that the results are due to the independent variable only. A controlled variable is a factor kept constant throughout the experiment to ensure fair testing.
A person pushes a box with 100 N to the right. Friction opposes the motion with 80 N to the left. The box has a mass of 10 kg. Calculate the box’s acceleration.
A 1 kg object falls freely under the influence of gravity (a non-contact force). If gravity accelerates the object at 9.8 m/s2, what is the gravitational force acting on it?
A car is pushed with a force of 200 N, and it accelerates at 2 m/s². What is the car’s mass?
100 kg (calculated using Newton’s Second Law, F=ma, so m= F/a = 200/2 = 100
A 10 kg object weighs 98 N on Earth. What would its weight be on the Moon, where gravity is approximately 1/6th of Earth’s gravity?
W = m⋅g = 10kg × (9.8/6) = 10 × 1.63 = 16.3N. The weight is 16.3 N
When drawing a conclusion, what two key aspects should you consider to determine if your hypothesis was supported?
You should consider the data collected and whether it aligns with the prediction made in the hypothesis. Additionally, consider any limitations or errors that might have influenced the results.