Lesson: Force as Rate of Momentum Change Physics • 9th Grade

In this lesson, we will learn how to relate the rate of change of momentum of an object to the force acting on it, using the formula ∆p = FΔt.

Lesson Plan

Students will be able to

use the formula in all combinations.

Lesson Presentation

Lesson Video

Lesson Explainer

Sample Question Videos

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05:10
04:05

Lesson Worksheet

Q1:

An average force of 12.5 N is applied by moving air to a bicycle and its rider, of total mass 80 kg, while it is windy that day. The force is applied throughout a time interval of 0.8 s as the gust of wind is very brief. The wind blows from directly behind the bicycle. What is the total momentum change?

Q2:

A man running on a road had a momentum of 360 kg⋅m/s. The road ahead of the man was covered by sand. The man ran through the sand for 12 seconds and his momentum when he had crossed the sand-covered part of the road was 330 kg⋅m/s. What average force did the sand apply to the man while he ran across it?

Q3:

A force of 10 N is applied to an object for 3 seconds, acting in the direction in which the object is moving. How much does the momentum of the object change?