The acceleration of an object is
directly proportional to the net force acting upon it. The constant
of proportionality is the mass.
F=MA
A=F/M
F = Force = A push or pull M = Mass A= Acceleration = speeding up, slowing down or changing direction 
Mass
= 5 kg 
Let’s assume that the wheels of a 5kg car apply 10 N of force. What is the net force if friction and drag are negligible? The net force would
equal 10 

What is the acceleration of the car? 
Force 
= MA 


10 
= 5A 


Acceleration = 
2 m/s^{2} 





Mass = 6 kg 
What is the net force if the wheels of the 5kg car apply
10 The net force would
equal 3 

What is the acceleration of the car? 
Acceleration 
= F/M 



Acceleration 
= 3/6 



Acceleration = 
0.5 m/s^{2} 






Mass = 10 kg 
A rocket is added to the car and applies an additional
force of 10 The net force would
equal 13 

What is the acceleration of the car? 
Acceleration 
= F/M 



Acceleration 
=13/10 



Acceleration

=1.3 m/s^{2} 

Big masses are hard to accelerate. Big masses require big forces to change speed. 

Small masses are easy to accelerate. Small masses require small forces to change speed. 

Objects move in the direction they are pushed or
pulled. Objects accelerate more quickly when a greater force is used. 
Assume
that both steam engines below apply the same amount of force.
A heavy train has a difficult time accelerating. Big masses require big forces to change speed. 

Acceleration = 
Force / Mass 
Acceleration = 
100% / 100% 
Acceleration = 
1 
When
the same force is applied to a less massive train its acceleration is
greater. Small masses require small forces to change speed. 

Acceleration = 
Force / Mass 
Acceleration = 
100% / 10% of the big train 
Acceleration = 
10 times greater than the big train 