Transcript forces

FORCES
Test on Wednesday
speed
DvT
Acceleration
Forces
The Equation
F=ma
Force
Acceleration
Mass
Force equals mass times
acceleration
Logic
 Since all of the variables are directly related, then a
change in one DIRECTLY results in a change in
another
F=ma
If my force goes down, then my acceleration (or mass)
has to go down too.
Think
 If mass increases, what should happen to
acceleration?
 If acceleration decreases, what should happen to
force?
 If force increases, what should happen to acceleration?
 If mass decreases, what should happen to force?
Problems
 When our mass is in kg (kilograms) and our
acceleration is in m/s2 (meters per second squared)
then our force’s units will be:
kg(m/s2)  Newton (N)
Examples
 Timmy hits the gas petal of his car and it provides 5000
N of force onto the road. If his car and he have a mass
of 1850 kg, then how quickly do they accelerate?
 How much mass does a ball have that accelerates at
20 m/s2 when 15 N of force is applied to it?
You Try
 How much force is applied to an 18-wheeler with a
mass of 12,000 kg if it accelerates forward at 3.1 m/s2?
 You push a box that on the ground forward with 50 N of
force. If the box accelerates forward at 0.4 m/s2, how
much mass does it have?
Acceleration VS Velocity
 Remember! Acceleration and velocity are different!
 Therefore, if an object experiences an unbalanced
force it should ACCELERATE.
 What if you push something and it just moves a
constant speed?
 Forces are BALANCED.
Friction
Engine