Forces key questions Flashcards
define resultant force
A single force found by adding up all of the individual forces acting on an object
typical cycling speed?
6 m/s
Name five factors that can affect reaction time
tiredness, drugs, alcohol, poor visibility, speed
Write the equation linking acceleration, change of in velocity and time?
acceleration = change in velocity/time
define ‘scalar quantity’
size but no direction
Write the equation linking force, spring constant and extension
force = spring constant x extension
what is a force?
a push or pull
4 examples of contact forces
friction, air resistance, tension and normal contact force
According to Newton’s second law, what is the acceleration of an object inversely proportional to?
mass
State newton’s second law (rad)
The resultant force will cause the object to accelerate in the direction of this force
define spring constant
the stiffness of the spring
is distance scalar or vector?
scalar
What is the equation linking force, mass and acceleration?
force = mass x acceleration
What is the law of conservation of the momentum?
Total momentum before = total momentum after
What happens to an elastic object after the limit of proportionality?
Inelastic deformation (It will not return to its original length)
when is work done on an object? (dd)
When a force moves at a distance in the direction of that force
where does the weight of any object act from?
the centre of mass
According to Newton’s second law, what is the acceleration of an object proportional to?
the resultant force
3 examples of non contact forces
gravitational, electrostatic and magnetic
What is the inertial mass of an object?
How difficult it is to change the velocity of an object
what is the typical reaction time?
Between 0.2 and 0.9 s
Describe the motion of an object that is initially stationary, when the resultant force is zero
remains stationary
is velocity scalar or vector?
vector
What do we call the reluctancy of an object to change motion?
inertia
define non contact forces
forces that can act even when the objects are not touching
define weight
the force acting on an object due to gravity pulling on its mass
is speed scalar or vector?
scalar
What happens to the temperature of an object when work is done against friction?
it increases
what is thinking distance?
Distance travelled during reaction time
How do you calculate the distance travelled from a velocity-time graph?
Calculate the area under the curve/line of the selected time
What happens to an elastic object up to the limit of proportionality?
Elastic deformation (It is able to return to its original length)
State newton’s first law (vrf)
The velocity of an object will only change if there is a resultant force
what is acceleration? (cv)
the change in velocity over a given time period
typical running speed?
3 m/s
typical walking speed?
1.5 m/s
what equipment is used to measure weight (forces)?
newtonmeter
how do you calculate resultant force? (-+)
Subtract forces acting in the opposite direction and add forces acting in the same direction
What is the name for the constant speed a falling object reaches when the resistive force is equal to its weight?
terminal velocity
Write equation linking the momentum, mass and velocity?
momentum = mass x velocity
what is displacement?
a distance with direction
How do you calculate acceleration from a velocity-time graph?
by calculating the gradient
what is stopping distance?
Thinking distance + braking distance
what equation links weight, mass and gravitational field strength?
weight= mass x gravitational field strength
When moving in a circle at constant speed, why is velocity constantly changing?
direction changes as velocity is a vector quantity
Write the equation linking distance, velocity and time
distance = speed x time
define mass
the amount of matter an object contains
Write the equation linking work done, force and displacement?
work done = force x displacement
How many Joules is one Newton-metre?
1 joule
Name five factors that can affect braking distance
Speed, worn tyres, worn brakes, icy roads, damaged roads
If an object is falling due to gravity on Earth, what acceleration does it have?
9.8 m/s2
State the relationship between force and extension for an elastic object
they are directly proportional
Describe the motion of an object that is initially moving, when the resultant force is zero
Continues to move a constant speed in the same direction
what is braking distance?
Distance travelled once the brakes have been applied
State three properties of a pair of forces which obey Newton’s third law
The forces are the same type, they act of 2 different bodies and have the same line of action
State newton’s third law
When two objects interact they exert equal and opposite forces on each other
define contact forces
forces that can only act when objects are touching
define ‘ vector quantity’
vector quantities have both size and direction
How do you calculate the speed of an object from a distance-time graph?
by calculating the gradient
is displacement scalar or vector?
vector
