Forces Flashcards
(12 cards)
What is a scalar quantity?
A scalar quantity is a quantity that only has magnitude (size), this includes: speed, mass, time and energy.
What is a vector quantity?
A vector quantity is a quantity with both magnitude and direction, this includes: displacement, velocity, acceleration, force and momentum.
What is Newton’s third law?
“Every action has an equal and opposite reaction”
What is weight?
Weight is the gravitational force you experience on earth. Weight is measured in Newtons (N)
What is the centre of mass of an object?
The weight of an object acts from a single point known as the centre of mass.
What is resultant force?
When there are 2 or more forces acting on an object the overall force can be represented by on arrow.
How do you calculate resultant force when the forces are at right angles?
When the forces are at right angles to each other then you draw one line where the force ends up and use pythagoras to find the total force. Think of it like vectors.
When an object is on a ramp how do you find the normal and parallel forces?
Normal = W cos (30)
Parallel = W sin (30)
What is a moment?
If a force causes an object to rotate then it has a turning effect - this turning effect is called a moment. It is measure in Newton metres (Nm)
What is the principle of moments?
If an object is balanced then the sum of all the clockwise moments is equal to the sum of all the anticlockwise moments.
What is a gear?
A gear is a device used to transmit the rotational effects of forces from one place to another
How do gears work?
Cog A has a specific moment and the force of this moment is transmitted to Cog B at a point of contact. Cog B is a different size and so the turning effect of Cog B will be different. If Cog B is bigger the turning effect will be bigger and vice-versa.
