# Multiple forces acting on an object

##### Intros
###### Lessons
1. Introduction to multiple forces acting on an object
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How to draw a free body diagram
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Normal force
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Force of friction
##### Examples
###### Lessons
1. Understanding gravity

What is the thrust needed to launch a 0.567 kg model rocket straight up, accelerating it a rate of 18.5 $m/s^{2}$?

1. Understanding normal force

A 2.50 kg briefcase rests on a table.

i. Calculate the normal force acting on the briefcase.

ii. A rock weighing 5.0 N is placed on top of the briefcase. Draw free body diagrams for the rock and the briefcase. Calculate the normal force from the table acting on the briefcase.

iii. The rock is removed and the briefcase is lifted by a force of 27.0 N straight up. What is the normal force from the table acting on the briefcase?

1. Multiple forces acting on an object

Calculate the normal force and force of friction acting on a 0.375 kg book that is pushed across a desk with a force of 1.24 N [right] and accelerating at 0.364 $m/s^{2}$ [right].