Mechanics Flashcards
(36 cards)
What is the difference between a scalar and a vector
Scalar - Magnitude
Vector - Magnitude & Direction
Give examples of 3 scalars & vectors
S - Time/Temperature/Mass
V - Velocity/Acceleration/Force
Define resultant force
A singular force that represents the effects of all the other forces acting on a body
Definition of a moment
The moment of a force is the force applied multiplied by the perpendicular distance to the pivot
What is the equilibrium of a moment
Forces acting upwards are equal to the forces acting downwards
What is the force through a pivot
Zero
What is the principle of moments
The sum of anti clockwise moments is equal to the sum of clockwise moments
What is a couple
A pair of coplanar forces of equal size that causes a turning effect when there is no resultant forces
What is the formula for a couple
Distance between the two forces multiplied by a singular force
Why is weight not a factor in suvat
F = mg F = ma ma = mg Mass cancels out
How do we find centre of mass
A bob hanging from a string hung and an object hanging at the same point, the bob will pass through the centre of mass. Rotate object
What is meant by centre of mass
The point where mass acts from (centre)
How do we find velocity of a curved displacement time graph
Draw a tangent at a point and find the gradient of tangent
What shows displacement in a velocity time graph
Area underneath
What does the area under an acceleration time graph represents
Change in velocity
Explain a acceleration time graph
Above x axis - Acceleration
On x axis - No acceleration
Below x axis - Deceleration
List all suvat equations
S = ut+1/2at^2
S = 1/2(u+v)t
S= vt-1/2at^2
V = u+at
V^2=U^2+2as
Explain fundamentals of projectile motion
X axis uses S = D/t - y axis uses SUVAT
Vertical & Horizontal velocity split into components using trigonometry
No acceleration on x axis
Time is the same over both
Acceleration in y is 9.81 (g)
Assumptions when using SUVAt
No air resistance
Object is a particle
Newtons 1st law
A resultant force is needed to change velocity
Newtons 2nd law
F = MA If there is a resultant force, there is an acceleration (acceleration is proportional to force)
Newtons 3rd law
If an object A exerts a force on object B, the object B exerts and equal but opposite force on object A
What is meant by free fall
Only acting downwards force is the weight force
How do we test for gravity (practical)
Diagram: Magnet Ball Height
Method: Measure height, drop ball and time until it hits the bottom, repeat with different heights, draw graph of heigh against time squared, line of best fit, gradient = g
