Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Force is a push or a pull acting on an object. It can change the shape, size, speed, or direction of an object.
Common types of forces include Gravitational force (pulls objects toward Earth), Frictional force (opposes motion), and Magnetic force.
Work is said to be done only when a force applied to an object causes it to move a certain distance in the direction of the force. If there is no movement, .
Energy is the capacity or ability to do work. It exists in many forms like Kinetic energy (energy of motion) and Potential energy (stored energy).
Simple Machines are basic mechanical devices that make work easier by either changing the direction of force or increasing the amount of force applied.
The six types of simple machines are: Lever (e.g., see-saw), Pulley (e.g., well bucket), Inclined Plane (e.g., ramp), Wheel and Axle (e.g., bicycle pedal), Wedge (e.g., axe), and Screw (e.g., bottle cap).
A Lever consists of three parts: the Fulcrum (fixed point), the Load (object to be moved), and the Effort (force applied).
📐Formulae
💡Examples
Problem 1:
A student pushes against a heavy stone wall with a force of for 10 minutes, but the wall does not move. Calculate the work done.
Solution:
Explanation:
According to the formula , since the wall did not move, the distance () is . Therefore, . No work is done if there is no displacement.
Problem 2:
Identify the type of simple machine used in a pair of scissors and explain how it works.
Solution:
Lever
Explanation:
Scissors are a type of complex lever (specifically two first-class levers joined). The screw in the middle acts as the fulcrum (), the handles are where the effort () is applied, and the blades cutting the paper represent the load ().
Problem 3:
Which force helps a ball thrown upwards to come back to the ground?
Solution:
Gravitational Force
Explanation:
Gravity is the force by which the Earth pulls all objects towards its center. When a ball is thrown up, the earth's gravity acts on it, slowing it down and eventually pulling it back down.