Forces, Circular Motion and Momentum Flashcards
What is the name given to the single force that is equivalent to all the other forces acting on a given object?
The resultant force.
State Newton’s first law for a stationary object.
If the resultant force on a stationary object is zero, the object will remain at rest.
State Newton’s first law for a moving object.
If the resultant force on a moving object is zero, the object will remain at constant velocity (same speed in same direction).
State the defining equation for Newton’s Second Law.
F = ma
Resultant force = Mass x Acceleration
State Newton’s Second Law in words.
An object’s acceleration is directly proportional to the resultant force acting on it and inversely proportional to its mass.
What is weight?
The force that acts on an object due to gravity and the object’s mass.
Equation for weight
W =mg
Weight = mass x gravitational field strength
Unit for weight
The Newton (N).
What is the unit used for gravitational field strength?
N/kg
Gravitational field strength on earth
9.8 N/kg which is rounded to 10 N/kg
What piece of equipment can be used to measure an object’s weight?
Newton Meter
When can an object travelling at a constant speed not have a constant velocity?
When the object is changing direction; for example, moving in a circle.
Why does an object travelling at a constant speed in a circle not have a constant velocity?
● Speed is a scalar quantity
● Velocity is a vector quantity which means it can only be constant if the direction is constant
● In circular motion, the direction is continuously
changing
● Velocity is constantly changing
What is the resultant force that acts on an object moving in a circle called, and in which direction does it act?
centripetal force and it acts towards the centre of the circle.
What is inertial mass?
● A measure of how difficult it is to change a given object’s velocity
● The ratio of force over acceleration
