Vectors Flashcards
Physical quantity
A measurement of something
Speed equation
Distance (m)/ Time (sec)
What is always on the x-axis
Time
How to find the displacement of a velocity time graph?
The area under the velocity time graph gives displacement
Upthrust/ buoyancy is a force cause by…
Pressure
In a free fall diagram what is not taken into account
Air resistance
What does upthrust depend on?
The density and volume of the liquid
When firing a projectile what are the horizontal and vertical speeds?
Horizontal speed stays constant
Vertical speed is only affected by gravity (and therefore has an initial velocity of 0)
For thinking distance, what is speed directly proportional to?
The distance
d=vt
v=d
For braking distance, what is speed directly proportional to?
Initial velocity squared
s=u^2
What are three methods you can use to measure acceleration due to gravity?
- Using a timer and ball
- Using 2 light gates (A and B)
- Using an electromagnetic timer
What does the mass of an object depend on?
The amount of matter it contains (density)
A net (resultant) force acting on an object will…
Make the object accelerate in the direction of the net force.
F=ma
Mass
kg
It’s always constant for a specific object or particle
Weight
Nkgms-2
Magnitude is variable (as depends on the location, gravitational field strength)
What’s the equation for weight
W=mg
What’s the value of g for an object during free fall
9.81m/s2
How can you determine the weight of an object
Use a Newtonmeter which is calibrated to show the gravitational force acting on an object in Newtons.
Centre of gravity
Where the weight appears to act from
When is the centre of gravity equal to the centre of mass
When we are in a uniformed gravitational field
When does an object become unstable?
As soon as the centre of mass is off the base
Centre of mass
Defined as the point where the mass is centred (the point has no turning effect)
How do you find the centre of mass for an irregular 2D object?
Use a plumb bob, which makes a plumb line, that tells you the direction gravity is acting (downward direction)
Moment
The turning effect of a force
Where would a moment act?
Around a pivot
Which direction can a moment act?
Clockwise or anti-clockwise
Moment equation
Moment= force x perpendicular distance to the line of action from the force
Nm= N x m
In moments when is the object in equilibrium
When the forces and moments are balanced
F1d1=F2d2
Couple definition
Is defined as 2 equal and opposite forces acting on a body but on different lines of action
Torque
The moment produced by a couple
When does an object topple over?
When its weight is outside its base
What does stability depend on?
The width of the base
The height of the centre of mass
Unstable equilibrium
Push an object (apply a force) and it won’t return back to its original position
Stable equilibrium
An object will return back to its original position
