Forces Flashcards
What do forces do
They act on bodies
Make them change shape
Make them change speed
Make them change direction
What happens when body A exerts a force onto Body B
B exerts an equal and opposite force onto body A
What is a friction
When 2 objects rub against each other
Always opposes motion
Examples of friction
Pushing a cardboard box
Driving a car along the road
What are forces measured in?
Newtons - N
What type of quantity are forces?
They are vector quantities, as such we must consider direction
How do you determine the resultant force on a object
Add together all the forces acting on the object
Fr = F1 + F2 + F3 …. + FN
What are the qualities of Newtons 1st law?
The forces are balanced
Fr = 0
The system is said to be in a “state of equilibrium”
What are the 2 possible states of motion when a body complies with Newtons 1st Law
At rest/ stationary
Moving with a constant velocity
What happens when a body complies with Newtons 2nd Law
The forces are unbalanced
There is a restaurant force - Fr
The object with be forced to accelerate or decelerate
It will change speed and change direction
What is direct proportionality
When the amount of one quantity increases/decreases the other quantity also increases/decreases by the same amount
What is the equation for FR
FR =ma
Resultant force = mass x acceleration
What is inverse/indirect proportionality
E.g S = d/t S ∝ 1/t
“S is inversely proportional to t”
When s is x2 , t is /2
When s is x4.1, t is /4.1
When s is /13.3, t is x13.3
State Newton’s first law of motion?
the forces on a system are balanced and so FR = 0, the
object will not accelerate. The object has 2 possible states of motion;
➢ Stationary.
➢ Moving at a constant velocity.
State Newton’s second law of motion?
FR = m a, and so FR / m = a
The acceleration, a of a body is directly proportional to the resultant force, FR, and inversely proportional to the mass, m.
