Balanced and Unbalanced Forces
What is the difference between balanced and unbalanced forces?
Balanced forces are equal in size and opposite in direction, resulting in no change in motion. Unbalanced forces cause a change in motion.
What happens to an object’s motion when an unbalanced force is applied?
It changes speed, direction, or both.
What instrument is used to measure force?
A force meter (spring scale).
What force pulls objects towards the centre of the Earth?
Gravity.
Name one simple machine that helps reduce the force needed to move an object.
Lever, pulley, inclined plane, wedge, screw, or wheel and axle.
If an object is not moving, what can you say about the forces acting on it?
The forces are balanced.
Give an example of an object that starts moving due to an unbalanced force.
A soccer ball being kicked.
What unit is force measured in?
Newtons (N).
How does mass affect the force of gravity on an object?
The greater the mass, the greater the gravitational force.
How does a lever make work easier?
It increases force by using a fulcrum to create a mechanical advantage.
A person pushes a box with a force of 20N to the right, while friction applies a force of 20N to the left. What happens to the box?
The box does not move because the forces are balanced.
What happens to the motion of a ball rolling on the ground if no external forces act on it?
It will continue moving at the same speed in the same direction.
How can arrows be used to represent forces?
The length shows the magnitude (strength) of the force, and the direction shows where the force is acting.
Would an object weigh more on Earth or the Moon? Why?
Earth, because Earth's gravity is stronger than the Moon’s.
What is the main purpose of using a pulley?
To change the direction of a force and reduce the effort needed to lift an object.
A car is moving at a constant speed. Are the forces balanced or unbalanced? Explain.
Balanced, because there is no change in motion (no acceleration).
A soccer ball is rolling and suddenly stops. What force might have caused it to stop?
Friction between the ball and the ground.
If two equal forces act in opposite directions on an object, how do you show this using arrows?
Two arrows of equal length pointing in opposite directions.
A bowling ball and a feather are dropped at the same time in a vacuum. Which lands first? Explain why.
They land at the same time because there is no air resistance, so gravity affects them equally.
A person uses a ramp to push a heavy box up into a truck. How does the ramp reduce the amount of force needed?
It spreads the force over a longer distance, making it easier to push the box.
Describe what happens when two people push on an object from opposite sides with different amounts of force.
The object will move in the direction of the stronger force.
If a moving object has a large mass, does it require more or less force to change its motion? Why?
More force, because a larger mass has more inertia (resistance to change in motion).
A force arrow diagram shows one long arrow pointing forward and a shorter arrow pointing backward. What does this tell you about the object's motion?
The object is accelerating in the forward direction.
If gravity pulls all objects towards the Earth, why don’t we feel ourselves being pulled towards other objects, like a table or a chair?
The force of gravity between small objects is tiny compared to Earth's gravity.
A seesaw is an example of what type of simple machine? How does its position affect how much force is needed to lift a person?
A lever; moving the fulcrum closer to the heavier person makes it easier to lift them.