forces and transfer of energy Flashcards
What is the formula for work done and what is the SI unit of work done?
Formula:
Force (N) x Distance (metre)
SI unit:
Joule (J)
What is one characteristic of mass and weight?
Mass:
- the mass remains unchanged in different locations
Weight:
- the weight of an object varies in different locations
What are some ways to overcome friction?
Hint: There are two main ones!
- Using lubricating oil or grease
Lubricating oil or grease makes a surface smoother. Hence, an object can move across the surface with less friction, and it does not wear out so quickly. - Using ball bearings, rollers, or wheels
Conveyor belts are fitted with rotating metal rollers to transport heavy objects easily.
Wheels are fitted over heavy objects such as refrigerators, shelves, or machines so that they can be moved easily.
When is work done?
Work is done only when ALL three conditions are fulfilled:
1. A force is applied to the object
2. The object moves
3. The object moves in the same direction as the applied force
What is the law of conservation of energy?
Energy cannot be created or destroyed. It can only be converted from one form into another.
What is elastic force?
Elastic force is a contact force that comes into play when an object is stretched or compressed from its original shape.
What is the SI unit and the symbol of force?
Newton (N)
What are examples of contact and non contact forces?
Contact:
1. Friction
2. Elastic force
Non-contact force:
1. Magnetic force
2. Gravitational force
What is frictional force (friction)?
Friction is a contact force that opposes the motion between two surfaces in contact. It occurs when two objects are in direct physical contact and one attempts to slide or move across the surface of the other.
What is the weight formula?
Weight = mass x gravitational field strength (10)
(or W = m x g)
What is the pressure formula and SI unit?
Formula:
Force (N) ➗ Area (metre square)
SI unit:
Pa (pascal) or N/metre square
What are the two factors that affect pressure?
- Amount of force applied
- When the area of contact is kept constant, the greater the force applied, the greater the pressure - Area of contact
- When the force applied is kept constant, the smaller the area of contact, the greater the pressure
What is a force?
A force is a push or pull.
Define mass and weight.
Mass is the amount of matter in an object.
Weight is the amount of gravitational force acting on an object.
What is weight?
Weight is the amount of gravitational force acting on an object
What is a disadvantage of friction?
Wear and tear.
It causes shoes, tyres, moving parts on machines, or other objects that are used for moving to wear out.
What is magnetic force?
Magnetic force is a non-contact force exerted between magnets or between a magnet and magnetic substances.
What are some effects of forces?
- Changes in the state of rest or motion of an object
- When a force is exerted, leading to the transfer of energy, the following changes in the object’s state of rest or motion can be observed: - a stationary object starts to move
- a moving object experiences a change in speed
- a moving object comes to a complete stop
- a moving object changes its direction
- Changes in size and/or shape of an object
Examples:
- Stretching a rubber band
- Compressing a spring
- Crushing a soda can - Changes in pressure on an object
- The pressure on an object is affected by the amount of force applied to the area of contact with the object
- Pressure is defined as force per unit area.
What is the SI unit of mass and weight?
Mass: Kilogram (kg)
Weight: Newton (N)
What are the measuring instruments of mass and weight?
Mass:
1. Beam balance
2. Electronic balance
Weight:
1. Spring balance
