12PHY Mechanics Revision

Definitions

100

F_net=ma

What is Newton's 2nd Law?

200

If object A exerts a force on object B, object B exerts and equal and opposite (direction) force on object A

What is Newton's 3rd law?

300

An object will stay at rest or move at constant velocity unless acted on by a resultant force

What is Newton's 1st law?

400

The force on an object causing it to rotate.

What is torque?

500

Energy transferred when a force moves an object 

What is work done?

Conditions / assumptions

100

Net torque = 0Nm

What is a condition for equilibrium?

200

Net force = 0N (up forces = down forces)

What is a condition for equilibrium?

300

If no external forces act in the system/collision

When is momentum conserved?

400

Weight is the only force acting

What assumption is made for objects in projectile motion

500

= 0ms^-1 at the top

What is the vertical component of velocity in projectile motion at the highest point

Variables

100

9.8 ms^-2

What is g/acceleration due to gravity on Earth?

200

= F_gsinθ 

How do you calculate the friction force/parallel force for an object on a slope?

300

...then you cannot use v=d/t to make calculations

If the velocity is changing...
or
If the object is accelerating...

400

velocity x cosθ 

How do you calculate the horizontal component of velocity?

500

Because it is a 'restoring force' that opposes x direction

Why is there a - sign in the F=-kx equation?

Conditions / assumptions

100

Towards the centre of the circular path

What direction does F_c/a_c act?

200

At a tangent to the circle

What direction is velocity in circular motion?

300

air resistance is negligible

What can be assumed when making calculations about freefall/projectile motion

400

It results in a symmetrical parabola

What path would form if an object is in projectile motion from/to the same plane

500

This force acts down the slope

What direction would net force be on an object accelerating down a slope?

Variables

100

v_i = 0ms^-1

What is initial velocity if an object starts at rest
Or
What is the initial component of vertical velocity if an object is dropped

200

positive on the way up, negative on the way down

What are the directions of vertical velocity in projectile motion?

300

v_f = 0 ms^-1

What is the final velocity of an object that comes to a stop?

400

The arrows all point in the same direction around a triangle

What would a vector diagram look like for an object in equilibrium?

500

x 10⁶

What is the conversion factor for the prefix M (mega)?