Forces Flashcards
What is a force?
A force is a push or a pull.
It is a vector quantity.
It is measured in Newtons.
What are forces represented by?
Forces are represented using an arrow.
The length of the arrow represents the size of the force, and the arrowhead represents the direction.
A longer arrow represents a…
larger force
A shorter arrow represents a…
smaller force
What are the two types of forces?
Non-contact forces and Contact Forces
What are Contact Forces?
Contact forces need a physical contact to get created.
What are examples of contact forces?
Friction, Tension, Normal Reaction Force, Upthrust (Buoyancy Force), Thrust.
What are non-contact forces?
Non-contact forces get created due to fields (magnetic, electronic, gravitational).
What are examples of non-contact forces?
Weight (Gravitational Force)
Magnetic Force
Electrostatic Force
What’s normal reaction force?
When we keep an object on a surface, the weight of the object presses the surface down. The surface is giving a reaction on to the object according to Newton’s 3rd law.
What is Newton’s third law?
For every action (force) in nature, there is an equal and opposite reaction.
What is point of action?
Point of action of a force is from a point at the bottom of an object which is in contact with the surface.
Normal reaction should always be marked…
perpendicular to the surface.
What is friction?
Friction always opposes the motion. Frictional force always creates heat energy.
Friction is marked along…
the surfaces which are in contact.
Friction also gets created when…
an object is moving inside a fluid (liquid/gas)
Friction inside fluids is also known as…
drag force/air resistance/ water resistance/viscous force
What are examples of friction in fluids?
When a hot air balloon is acting up, so the air resistance is acting down.
When a parachutist is falling down, so the air resistance is acting up.
What is tension?
Tension gets created when the object is being stretched. Tension acts inwards from the two ends of the object. It’s like a rope is pulling back the person who is pulling it.
What is upthrust?
Upthrust acts upwards on an object that is fully/partially immersed in a fluid (gas or liquid).
What is buoyancy point?
The point from which the upthrust is acting.
Upthrust always acts…
vertically upwards.
What is weight/gravitational force?
Weight is the force acting on an object due to gravity. Weight depends on gravitational field strength.
Gravitational field strength…
is different on different planets. Higher the mass of the planet, higher the field strength.
Gravitational field strength is also known as what?
Gravitational acceleration?
What is the centre of gravity?
Weight always acts from the point known as the centre of gravity.
Weight always acts in which direction?
Vertically down.
What’s the equation for Weight?
Weight = Mass * Gravitational Field Strength
W = m * g
What are the effects of forces on objects?
A force can change the speed, direction and the shape of an object.
What is a resultant force?
A single force which can give the same effect as several forces added together.
What is a balanced force?
If the resultant force on an object is 0, the object is said to be balanced.
What should two forces have to be balanced?
The same magnitude, should act in opposite directions, and same line of action.
What are unbalanced forces?
If there is a value for the resultant force, the forces are unbalanced. The amount of unbalanced force is equal to the resultant force.
What is Newton’s First Law?
When the forces on an object are balanced, the object will remain at rest or move with a constant velocity along a straight line.
What does Newton’s first law reveal?
It reveals that there are two situations when the forces on an object are balanced:
-When they are at rest/stationary
-When they are moving at a constant velocity.
Unbalanced forces acting on an object cause it to…
accelerate/decelerate
This means that the velocity of the object changes with time.
What is Newton’s 2nd Law?
Newton’s second law states that the acceleration of an object is directly related to the net force and inversely related to its mass
Therefore: f = m * a
The magnitude of the object’s acceleration is …… to the magnitude of the resultant force.
directly proportional
The magnitude of the object’s acceleration is …. to the mass of the object.
inversely proportional
Resultant force is measured in what?
Newtons (N)
Acceleration is measured in?
m/s^2
Mass is measured in…
kilograms
What’s the difference between mass and weight?
Mass is the amount of matter an object contains while weight is the force acting downwards on an object due to gravity.
