Physics B 1 Flashcards
What is an objects centre of mass and how do you find it?
The centre of mass is where the mass of that object is concentrated. A freely suspended object will swing until it’s centre of mass is vertically below the point of suspension
Define a moment and how is it calculated?
A moment is the turning effect of a force
Moment of force in Newton metres = Force in newtons x Distance in metres
M = F x D
To make physical work easier where must the force be?
Force should be applied further away from the pivot.
What kind of objects are the most stable and why
Objects that are low and wide are the most stable because the centre of mass is closer to the ground
What is a time period and how is calculated
A time period is the time taken for a pendulum to swing from one side to the other again and it is Calculated by
Time period = 1\ frequency
What happens when pressure is applied to a liquid and how is pressure calculated?
It is transmitted equally in every direction
Pressure(pa) =
force(n) / Cross-sectional area(m squared)
What is centripetal force and what does the centripetal force of an object depend on?
The force that keeps something moving in a circle is called a centripetal force as if an object is travelling in a circle it’s velocity is constantly changing which means that it is accelerating but it is accelerating towards the centre of the circle
The faster it is moving the bigger the centripetal force has to be the same for the larger the mass
What is a magnetic field?
A magnetic field is a region where magnetic materials and also wires carrying currents experience a force acting on then
Describe a magnetic field within and around a coil of wire
Inside the coil is is strong and uniform.
Outside the coil it is made up of concentric circles
If the current is stopped the magnetic field disappears
How would you use Flemings left hand rule?
Your first finger points in the direction of the field and your second finger in the direction of the current.
Your thumb will then point in the direction of the force (motion)
How could you speed up an electric motor
More current
Stronger magnetic field
What is the definition of electromagnetic induction
The creation of a potential difference across a conductor which experiences a change in magnetic field.
What are dynamos used for?
They are often used on bikes to power the lights, the cog wheel at the top is positioned so that it touches one of the wheel. As the wheel moves round it turns the cog which is attached to the magnet.This creates an AC current to power the lights.
What happens when a magnet is moved in a coil of wire.
It induces a voltage
