Forces Flashcards
What are examples of forces?
Weight
Friction
Up thrust
Reaction
Air Resistance
What is Newton’s First Law?
An object will remain stationary or continue to move at a constant speed as long as the forces acting on it are balanced
What is Newton’s second law?
If there is a resultant force on an object then it will start to change speed (accelerate / decelerate)
What is Newton’s third law?
For every action there is an equal and opposite reaction
How do you calculate the resultant force?
Subtract the smaller number (force) from the larger number (force)
Force and extension are…
Directly proportional
What is Hooke’s Law?
The extension of an elastic object is directly proportional to the force applied to it, up to a point
What is the Hooke’s Law formula?
F (force) = K (spring constant) ➗ X (extension)
I how do you calculate the extension?
The new length minus the original length
What is force measured in?
Newtons
What is the spring constant measured in?
N/m
What is extension measured in?
metres
What is a moment?
Turning effect of a force around a pivot.
How do you calculate moments?
Force x Perpendicular Distance from the pivot
What are moments measured in?
N/m
How can an object reach equilibrium (be balanced)
Forces have to be the same on either side
What are the 6 vector quantities?
Displacement, velocity, acceleration force weight momentum
What are the 6 scalar quantities?
Temperature, mass, energy, distance, speed, density
Is force a scalar or vector quantity?
Vector
What is the relationship between unbalanced force, mass and acceleration?
Force = mass x acceleration
F = m x a
What is the relationship between weight, mass and gravitational field strength?
Weight = mass x gravitational field strength
W = m x g
What is the stopping distance of a vehicle made up of?
Thinking distance and braking distance
What are the factors affecting vehicle stopping distance?
Speed, mass, road condition and reaction time
What are the two main forces that act on a falling object?
Weight and Air resistance
What happens when an object falls?
Reaches terminal velocity
As a parachuter drops, what happens?
It accelerates, reaches terminal velocity (forces balance), air resistance = larger than gravitational force on parachute, decelerates, opens and reach new terminal velocity, becomes equal and slower
What can effect thinking distance?
Speed of car, Alcohol/drugs, age and eyesight
What can effect braking distance?
Speed of car, road, tyre and brake condition
What can force change?
Speed, shape or direction of a body
