Newton's Laws of Motion

Understand the relationship between force, mass, and acceleration quantitatively (mathematically).

​I can...

Newton's 1st Law

Newton's 2nd Law

Remember, you have the equation F=ma but you need to change it depending on what you are trying to find. But how did we get those units?

Using the equation a=F/m

Answer: 2m/s²

​If we replace the equation

​with the units we get

​which is the same as

​Units are like numbers, so the kg's cancel each other out like 5/5 is 1

​which is correct because it's the unit for acceleration which is what we were trying to find.

Let's try increasing the force

a = F/m

a = 20N/5kg

a = 4 m/s²

^{I doubled the force and it actually doubled the acceleration}

​Original problem

a = F/m
F=10N m=5kg

a = 10N/5kg

a = 2 m/s²

Let's try increasing mass

a = F/m

a = 10N/10kg

a = 1 m/s²

^{I doubled the mass and it halved the acceleration}

​Original problem

a = F/m
F=10N m=5kg

a = 10N/5kg

a = 2 m/s²

Newton's 3rd Law

Understand the relationship between force, mass, and acceleration quantitatively (mathematically).

​I can...

​If you increase mass OR acceleration, it will increase force. If you decrease mass OR acceleration, it will decrease force.

F = ma

increase mass

same acceleration

= more force

​If you increase an object mass but don't apply more force, the object acceleration will lessen. If you decrease its mass then it's acceleration will increase. a = F/m

increase mass

same force

= less acceleration

If you increase the amount of force you put on anything (as long as it's greater than the object's inertia), it will increase its acceleration.

a = F/m

increase force

same mass

= more acceleration