Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A Force is a push or a pull acting upon an object as a result of its interaction with another object.
Force can make a stationary object move, stop a moving object, change the direction of motion, or change the shape of an object. This is often denoted as .
Friction is a special type of force that acts between two surfaces that are sliding, or trying to slide, across each other. It always works in the direction opposite to the direction in which the object is moving.
Gravity is the invisible force that pulls all objects toward the center of the Earth. It is the reason objects fall down when dropped.
Work is done when a force applied to an object causes that object to move a certain distance. If there is no movement, the work done is zero.
Energy is the capacity or the ability to do work. Without energy, we cannot apply force to perform tasks.
Common forms of energy include Mechanical Energy, Heat Energy, Light Energy, and Sound Energy. Energy can be transformed from one form to another, such as in a bulb.
📐Formulae
💡Examples
Problem 1:
A girl pushes against a heavy stone wall with a lot of force, but the wall does not move. Calculate the work done.
Solution:
Joules
Explanation:
In science, work is only done if the object moves. Since the distance moved () is , the formula results in .
Problem 2:
Which force helps us to walk on the ground without slipping?
Solution:
The force of Friction ()
Explanation:
Friction between our shoes and the ground provides the necessary grip. On very smooth surfaces like ice, friction is low, making it hard to walk.
Problem 3:
Identify the type of force: An apple falling from a tree toward the ground.
Solution:
Gravitational Force (Gravity)
Explanation:
The Earth exerts a pull on all objects, represented by the acceleration due to gravity , pulling the apple downwards.