Physics PAPER2 forces Flashcards
What are the vector quantities
Force, velocity, acceleration
What are the scaler quantities
Time, mass, speed, energy, temperature
What do vector quantities have
A size and direction
What do you scaler quantities have
Just have a size
What is a force
A force is a push or pull that acts on an object
What is a contact force
When two objects or touching for a force to act
What is a noncontact force
When objects aren’t touching for the force to act
What are examples of non-contact forces
Magnetic force, gravitational force, electrostatic force
What are examples of contact forces
Friction, air resistance, tension
What is an interaction pair
When the forces on two objects are equal in size but act in opposite directions
Give an example of and interaction pair
The gravitational attraction between the Earth and the Sun
Define weight
The force acting on an object due to gravity
What is the weight of an object depend on
It’s mass and strength of the gravitational field it’s in
What is weight measured in
Newtons
How do you calculate the weight of an object
Weight= mass x gravitational field strength
Calculate the weight in newtons of a 5kg mass on Earth with 9.8 newtons
9.8 N/kg x 5kg = 49N
What is a resultant force
The overall force on a point or object
How can you find the resultant force
Add together forces acting in the same direction, take away any going in the opposite direction
A trolley is pulled by two children one child pose the trolley with a fourth of 5 N to the left the other poles the trolley with a fourth of 10 N to the right what is the resultant force?
F= 10N - 5N = 5N
What happens when a force moves an object through a distance
Energy is transferred and work is done on the object
Doing work against frictional forces causes energy to be transferred to what energy store
Thermal energy store of the object
Give an example of a frictional force that causes temperature of the object to increase
When you push something along a rough surface for example of carpet
What is the equation for how much work has been done
W= Force x distance(in metres)
A fourth of 20N pushes an object 20cm work out the work done on the object
20 x 0.2 = 4
What three things can transfer energy
Bending, compressing, stretching
What is it called when objects can go back to its original shape after a force has been removed
Elastically deformed
Give an example of an elastically deformed object
A spring
What is the equation to work on what a force is
Force = Spring constant(in metres) x extension(in metres)
The spring is fixed at one end, and a force of 1 Newton is applied to the other end, causing it to stretch. The spring extends by 2 cm calculate the spring constant of the spring
1 N divided by 0.02 m = 50 N/m
What happens on a graph when the relationship is nonlinear
The straight line begins to bend
Explain the required practical to investigate the link between force and extension
Measure the mass of each mass, calculate it away, measured the original length of the spring, Adam asked for the sprint and allow it to come to rest, record the force and measure the new length of the spring, repeat until you’ve added all the masses and then plot of force extension graph of your results
What is the equation for how to find the extension
New length - original length
How do you calculate distance
Distance in metres= speed in m/s x Time in seconds
Sprinter runs 200 m in 25 seconds calculate the speed
200 m divided by 25 seconds = 8 m/s
What is acceleration
The change in velocity in a certain amount of time
How can you find the acceleration
Acceleration (metres) = change in velocity metres per second divided by time taken in seconds
The steeper The distance on a graph means the
The faster it’s going
What does a straight uphill section mean on a graph
Steady pace it is travelling at
The flat section on a graph is at stationary please which means
It’s stopped
What does a curve represent on a graph
Going up it means acceleration going down it means deceleration
How do you calculate the gradient on a graph
Choose two points and the change in the vertical axis divided by the change in the horizontal axis
What is Newton‘s first law
A resultant force is needed to make something start moving speed up or slow down
What is new in second law
The force acting on an object and the acceleration of the object are directly proportional
The Lord of the resultant force acting on an object the more the object
Accelerate
What is Newton‘s third law
When two objects interact the forces they exert on each other are equal and opposite
What will happen to skater A when she pushes on skate B
She feels an equal and opposite forth from skate of his hand, both skaters feel the same sized force in opposite directions so then they accelerate from each other
