Lesson: Distinguishing Weight from Other Forces Physics • 9th Grade

In this lesson, we will learn how to distinguish between the effects of the weight of an object and other forces acting on it.

Lesson Plan

Students will be able to

recognize that weight force is not necessarily equivalent to the net downward force acting on an object,
distinguish between and calculate forces acting in situations where a weight force acts in addition to other forces that might be confused with the weight force.

Lesson Video

Lesson Worksheet

Q1:

A car has a mass of 460 kg. The weight of the car is evenly supported by its four identical wheels. What force does each wheel apply to the ground?

Q2:

An astronaut who has a mass of 80 kg is in a space station that orbits Earth in free fall. The astronaut is floating in a room of the space station, touching a wall that is perpendicular to Earth’s surface with her hand. She pushes against the wall with a force of 20 N. What is her acceleration perpendicular to the wall?

Q3:

A child who has a mass of 30 kg jumps into the air and lands on the ground. The child hits the ground at a speed of 1 m/s and comes to rest 0.1 s after landing.

What is the child’s weight?

What is the average force applied to the ground by the child’s feet during the landing?