Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A force is a push or a pull that acts upon an object as a result of its interaction with another object.
Forces can cause an object to start moving, stop moving, change its speed, or change its direction of motion.
Forces are measured in units called Newtons, which are represented by the symbol .
Friction is a force that acts in the opposite direction to motion, occurring when two surfaces rub against each other.
Balanced forces occur when forces acting on an object are equal in size but opposite in direction, resulting in a net force of and no change in motion.
Unbalanced forces occur when the forces are not equal, causing the object to accelerate or change direction.
📐Formulae
💡Examples
Problem 1:
A student pushes a heavy crate with a force of to the right. At the same time, friction acts against the crate with a force of to the left. What is the net force acting on the crate?
Solution:
to the right
Explanation:
To find the net force (), we subtract the friction force from the push force because they are in opposite directions: .
Problem 2:
Two children are playing tug-of-war. Child A pulls with of force and Child B pulls in the opposite direction with of force. What is the net force, and will the rope move?
Solution:
; the rope will not move.
Explanation:
Since the forces are equal in size () but opposite in direction, they are balanced forces. .
Problem 3:
If you apply a force of to a ball and there is of friction, what is the total force making the ball move?
Solution:
Explanation:
With no opposing force like friction, the net force is equal to the applied push force: .