Forces Flashcards
adefine force
a push or pull that acts on an object due to it’s interaction with another object.
what are the factors of a vector?
both have a magnitude and a direction
give examples of contact forces
(3 marker)
- friction
- air resistance
- tension
give examples of non-contact forces
(3 marker)
- magnetic force
- gravity
- electrostatic force
give examples of non-contact forces
(3 marker)
- magnetic force
- gravity
- electrostatic force
what are the factors of a scalar quantity?
it only has a magnitude
examples of scalar quantities
(4 marker)
- speed
- distance
- mass
- time
examples of vector quantities
(4 marker)
- velocity
- displacement
- force
- acceleration
what are the forces acting on an object in a free body diagram?
- weight
- drag
- thrust
- lift
what happens to a spring when a force is applied?
(3 marker)
- compressed
- bends
- stretches
what are the two types of deformation?
- elastic deformation
- inelastic deformation
elastic practical
- place the spring upright attached
- there would be a little extension since it’s weight would extend it
- add weights and measure the increase in length
- the mass and extension is directly proportional
- the force and extension is direcly proportional
graph for elasticity
- the straight line would go from the origin suggesting force and extension are directly proportional
- this would all be elastic deformation (once the mass is removed it will return to normal)
- however once it reaches it’s limit, it will be permanently deformed.
what is it called when it reaches the point of inelastic deformation?
limit of proportionality or elastic limit
what is it called when it reaches the point of inelastic deformation?
limit of proportionality or elastic limit
equations for elasticity
- F = k e
- Ek = 1/2 k e^2
define deformation
the change in shape
1. length
2. cross sectional area
define moment
the rotation or turning effect of a force
equation for moment
M = F x d
unit for moment
Newton metre (Nm)
what is the rule for moments?
the sum of the total anticlockwise moment is equal to the sum of the total clockwise moment.
what is the effect of a smaller object on moment
the smaller the object, the larger the force needed since it is applied closer to the point.
what is the function of a lever?
transmits the turning effect of a force
gears
- the wheels turn in opposite ways
- the second wheel is 2x bigger
- therefore the turning effect is also 2x bigger on the second wheel
how is pressure created in gas?
- the particles collide with eachother and the wall
- as they collide they apply a force
why do particles colliding perpendicular generate more pressure than particles colliding at an angle?
- at perpendicular to the surface, all the force is exerted onto the wall and increases the pressure.
- particles colliding at angles dont exert all the force onto the wall, producing less pressure.
why do particles colliding perpendicular generate more pressure than particles colliding at an angle?
- at perpendicular to the surface, all the force is exerted onto the wall and increases the pressure.
- particles colliding at angles dont exert all the force onto the wall, producing less pressure.
equations for pressure
- p = F/A
- p = h p g
upthrust
- water particles around the box will collide with all sides of the surface
- since the bottom surface of the box is deeper there would be a larger upwards force.
- this is called upthrust.
what happens if the weight is larger than the object?
the object will sink
what happens if the upthrust is larger than the weight?
the object floats.
where is the density highest in the atmosphere?
the density is highest when its closest to the earth’s surface
what happens as the altitude increases?
(3 marker)
- there is less pressure and density with the higher the altitude
- so the number of particles colliding with the surface decreases
- there is more acceleration sinced there are no air particles
define atmospheric pressure
the air pressure created by collision between air particles and the surface
what happens if there are more gas particles?
(2 marker)
- the greater the number of gas particles, the higher the pressure, so more frequent collisions
- p = F/A
what happens if there are more gas particles?
(2 marker)
- the greater the number of gas particles, the higher the pressure, so more frequent collisions
- p = F/A
equations for acceleration
- a = change in velocity/time
- 2 a s = v^2 - u^2
what is acceleration measured in?
m/s^2
what does the gradient of a distance/time graph tell you?
the speed of the object
what does a flat line on a distance/ time graph tell you?
(2 marker)
- the object is stationary
- this is because the gradient is 0 meaning the speed must also be 0.
what does an increasing gradient/steeper line show?
acceleration
what does a decreasing gradient show?
deceleration
what does the grdient tell you on a velocity/time graph?
the acceleration
what is the constant positive gradient?
acceleration
what is the constant negative acceleration?
decelaration
what do flat lines on a velocity time graph tell you?
the velocity is constant and there is no acceleration
what does a steeper gradient tell you?
increase in acceleratiom
define terminal velocity
when velocity is constant
define stopping distance
the minimum distance required to stop a vehicle in an emergency
equation for stopping distance
thinking distance+ braking distance
what affects the thinking distance?
speed of the vehicle
reaction time
what increases the reaction time in stopping distance?
tired
drunk
drugs
distracted
what factors affect the braking distance?
condition of the brakes
speed + mass of car
condition of roads
