P3.2 Flashcards
What’s the centre of mass of an object?
Point where its mass can be thought to be concentrated.
When a suspended object is in equilibrium…?
Its centre of mass is directly beneath the point of suspension.
For any object in equilibrium, the sum of the anti-clockwise moments about any point…?
=the sum of the clockwise moments about that point.
How to increase centre of mass?
Make its base as wide as possible and its centre of mass as low as possible.
Why does an object topple over?
If the line of action of the weight lies outside the base of an object, there will be a resultant moment.
When does an object tend to topple over?
If the resultant moment about its point of turning is not at zero.
What does a hydraulic system use?
The pressure in a fluid to exert a force.
When an object moves in a circle its continuously changing direction, so…?
It is continuously changing velocity (accelerating). This acceleration is called the centripetal acceleration.
What’s centripetal acceleration?
The acceleration towards the centre of the circle of an object that is moving round the circle.
What does the centripetal force of an object depend on?
Its mass, its speed and radius of circle.
An example of oscillating motion?
A pendulum moving to and fro along the same line.
What does an electromagnet consist of?
A coil of insulated wire wrapped around an iron core.
Where are electromagnets used?
In scrapyard cranes, circuit breakers, electric bells and relays.
What is the force in a motor effect?
Increased if current or strength of magnetic field increased. At right angles to both direction of magnetic field and to wire, is reversed if direction of either current or magnetic field reversed.
What’s electromagnetic induction?
Process of creating a potential difference using a magnetic field. When a conductor cuts lines of a magnetic field, a PD is induced across the ends of the conductor.
