P10- Forces and motion Flashcards
What is a scalar?
A scalar is any quantity that has magnitude, but not a direction associated with it. A scalar can be added and subtracted.
What is a vector?
A vector is any quantity that has both magnitude and direction. It id illustrated by drawing an arrow above the symbol that is used to convey direction and magnitude.
How do you add vector?
If two similar vectors point in the same direction add them, but if they are going in different directions subtract them.
Examples of scalar
Density, temperature, frequency, wavelength, pressure, power, potential difference.
Examples of vector
Magnitude field, velocity, force, momentum, current, acceleration, displacement
Define a force
A force can change the shape of an object or change its state of rest or its motion.
What do you measure forces in?
Newtons
When is the resultant force zero
When all forces are balanced. This means stationary objects remain stationary and moving objects keep on moving at the same speed and in the same direction.
What happens when the resultant force is not zero?
A stationary object begins to move in the direction of the resultant force and moving objects speed up, slow down or change direction.
How do you calculate a moment?
Moment= force x distance
A force of 50N is exerted on a claw hammer of length 30cm, calculate the moment
M=FxD
M=50x0.3
M=15nm
Moments of the force, can be increased by…
Increasing the size of the force.
Using a spanner with a longer handle.
What do gears do?
They multiply the turning effect of the engine force
What happens when a gear is in low gear?
The bigger the turning effect is
A gear wheel of radius 20mm is used to turn another gear wheel of radius 10mm with a force of 80N. Work out the moment of a force of a 10mm wheel.
Moment= force x gear wheel radius = 80N x 0.010m= 0.80Nm
