Forces Flashcards
What quantity is displacement?
Vector quantity (has magnitude and direction)
What is braking distance?
Distance travelled under the breaking force
What is breaking distance affected by?
Road condition, vehicle condition, weather
What are some examples of vehicle condition that affect breaking distance?
Worn brakes or tyres, over or underinflated tyres
What are some weather conditions that affect breaking distance?
Snowy or icy roads
For a given breaking distance what does doubling the mass do?
Doubles the force required
For a given breaking distance, doubling the speed does what?
Quadruples the force required
What quantity is distance?
Scalar quantity (how far an object moves, doesn’t take into account the direction an object is travelling)
What is Newton’s first law?
An object will remain in the same state of motion unless acted upon by an external force
Define mass?
Amount of matter it contains and remains constant
What does the weight of an object depend on?
Depends on the Gravitational field strength where the object is and is directly proportional to its mass
What do vector quantities have?
Magnitude (size) and direction
What does velocity show?
Speed and direction of travel
Are mass and weight the same?
NO
What’s the difference between mass and weight?
Mass:Amount of substance present in an object
Weight:Force acting on mass
What is weight?
Force acting on mass due to gravity
What is mass?
Amount of substance present in an object
Arrows are used to present vector quantities, what does the length pf the arrow represent?
Magnitude (size)
Arrows are used to present vector quantities, what does the arrow point direction show?
The direction that the vector quantity is acting
What is a scalar quantity ?
Has magnitude (size) only like number of apples
What is an example of a scalar quantity?
Speed, distance
What is a vector quantity?
Has magnitude and direction
What is an example of a vector quantity?
Forces
What is Newton’s third law?
For every action there is an equal and opposite reaction
Examples of contact forces?
☆Friction
☆Air resistance
☆Tension
☆Normal contact
Examples of non-contact forces?
☆Gravitational force
☆Electrostatic force
☆Magnetic force
Define contact force?
Objects are physically touching
Describe the 4 steps of a skydivers terminal velocity?
1)Skydiver accelerates due to the force of gravity
2)Experiences frictional force due to air resistance,weight is a greater force so he keeps accelerating
3)Speed and resistive force increase, acceleration decrease
4)Resistive force increases until it is the same as weight, resultant force is zero, Skydive falls at terminal velocity
What is a more in depth explanation of newton’s third law?
Whenever an object exerts a force on another, the other object exerts a force back. Reaction force is the same type and equal size but opposite direction
Is amount of work done equal to energy stored in a spring?
Yes, provided the spring doesn’t go past the limit of proportinality
Define spring constant?
Indicates how easy it is to stretch or compressed a spring
What does it mean in terms of stiffness, the higher the spring constant?
The stifer the spring
How does travelling faster affect the braking force?
Travelling faster results in a larger breaking force needed
What happens if the breaking force is too great?
The brakes may overheat or tyres lose traction on the road = car skids
When resultant force acting on an object is zero what happens? (1ST LAW)
Object stationary=remains stationary
Object moving=continues moving
What is constant velocity?
To move at the same speed in the same direction
When does velocity change?
Velocity only changes of a resultant force is acting on it
When does the resultant force reach 0?
When resistive forces balance the force of gravity, now the object falls at a steady speed and is at terminal velocity
What energy is stored when a force stretches or compresses a spring?
Stores elastic potential energy
What are non-contact foreces?
Objects are physically separated, attraction and reclusion between objects
What is the limit of proportionality?
Point up to which an elastic object is directly proportional to applied forces
What is the extension of an elastic object directly proportional to?
Directly proportional to the applied force (straight line on graph)
What is done when a force causes an object to move?
Work is done on the object
Does work done require energy?
Yes (1J work done=1NM displacement)
What is elastically deformed?
Returns to shape after force is removed
Define inelastically deformed?
Doesn’t return to shape after
What is Newton’s second law?
Acceleration of an object is proportional to the resultant force acting on an object and inversely proportional to the mas of object
What happens to acceletation if resultant force is doubled? 2nd law
Resultant force doubled=acceletation doubled
What happens to acceletaton if mass is doubled? 2nd law
Acceleration halves
What equation sumariese Newton’s second law?
Force=mass x acceleration
How does the temperature of car breaks increase?
Work done (breaking) by this frictional force transfers the kinetic energy of the vehicle into heat energy, car breaks temp increase
What does calculating a mean do?
Reduces the effect of random errors
What are forces?
Vector quantities
What does gravitational field cause a mass to experience?
Causes mass to experience a force
What human reaction time affected by?
Drugs, alchol, tiredness, mobile phone use
How is stopping distance calculated?
Sum of thinking distance and breaking distance
What happens to energy when work is done?
Energy increases to overcome Friction
What happens to energy systems when work is done?
Energy transfers take place in a system when work is done
How does a vehicle stop?
Breaks need to apply force to wheels
What happens to the deceleration the greater the breaking force?
The greate the vehicle deceleration
Define speed?
Measure of how fast ahn object is travelling
What does the speed a person can walk/run depend on?
Factors like age
What is quantuty is speed?
Scalar quantity measured in m/s
Define acceleration?
Measure of how quickly an object speeds up, slows down, changes direction
What happens to a spring when the limit of proportionality is exceeded? (Relation)
•Doubling the force, no longer doubles the extension
•Non-linear Relation
•F-E graph stops being a straight line
Define resultant force?
When more or one force acts on an object they can be seen as one single force which has the same effect as all the forces acting together
Whst is the extension of an elastic object directly proportional to?
The applied force (produce straight line on F-E graph)
If 1Joule of work is done, what is the displacement value?
1joule work done = 1Nm displacement
