Impulse

This page examines impulse with force.

There is a relationship between Impulse (Δp) and Force (F) and Time (t).



Notice that the eqaution uses the net force or resultant force.
Best way to understand this, is to do an example!

Question 1
A force of 10N is applied rightwards on a trolley for 20s.

1.1. Write down an equation that relates force and time to impulse.
1.2. Calculate the impulse experienced by the trolley.
Question 2
A trolley experienced a 40 kg.m.s-1 impulse over a 10s period.

2.1 What is meant by impulse?
Impulse is the product of the resultant / net force acting on an object and the time the resultant / net force acts on the object.
2.2 Calculate the resultant force that is acting on the trolley.

Impulse and Newton's Second Law

State Newton's Second Law in terms of momentum
The resultant/net force acting on an object is equal to the rate of change of momentum of the object in the direction of the resultant/net force.

This can be expressed as an equation:




The Impulse - Momentum Theorem

Since :


And:


We can combine them to get:



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