Energy and Forces Flashcards
What is work done?
The energy transferred by a force, work done = force x distance in the direction of force
What is power?
The rate of doing work, power = work done / time taken
What is a watt?
1 watt means 1 joule of energy being transferred each second
How can the energy of a system be changed?
- Work done through forces
- Electrical equipment
- Heating a material
Give 3 examples of non-contact forces
- Gravity
- Magnetism
- Electrostatic charges
Do like poles or unlike poles attract?
Unlike poles attract, like poles repel
What does each force in a direction have?
A force acting in the opposite direction
What is the force that is opposite to a pushing force?
Friction, it acts to slow a moving object down
What is the normal force opposite to?
The weight of the object, the upthrust is also opposite to the weight, it is called upthrust when the object is falling down
In a free-body diagram what does the hypotenuse of the triangle represent?
The resultant force
How do you calculate a resultant force using a vector diagram?
Draw a parallelogram and measure the diagonal length
How do you resolve forces?
Draw the arrow to scale, draw dotted lines from the head of the arrow horizontally and vertically to the axis, measure the lengths of the x and y components
How do you calculate resultant force?
Biggest force - smallest force, the resultant force is in the direction of the biggest force
Why does an object topple?
When an object is straight, its weight acts directly down from the centre of mass, when the object tilts there comes a point where the line of action of the weight lies outside the block, there’s now an unbalanced moment acting on the block causing it to topple
How do you calculate a moment?
Moment (Nm) = force (N) x distance (m)
