2 - Mechanics Flashcards
What must be true when using SUVAT?
Constant acceleration
What does the gradient of a distance-time graph represent?
Speed
What does the gradient of a displacement-time graph represent?
Velocity
What does the gradient of a velocity time graph represent?
Acceleration
Describe the shape of a velocity-time graph when travelling with uniform acceleration
Straight line
Describe the shape of a velocity-time graph with non-uniform acceleration
Curved line
Compare velocity-time graphs for acceleration and deceleration
Acceleration: positive gradient
Deceleration: negative gradient
Define scalar quantity
Has magnitude but no fixed direction
Define vector quantity
Has magnitude and fixed direction
How is a vector quantity represented on a diagram?
-Arrow
-Arrow head = direction of quantity
-Length = magnitude
Describe the relationship between the perpendicular components of a vector
Independent of each other
State Newton’s 1st Law
An object will remain at rest/ constant velocity unless acted on by an external resultant force
State Newton’s 2nd Law
Acceleration of an object is directly proportional to the resultant force and inversely proportional to its mass
State the defining equation of Newton’s 2nd Law
F=ma
Describe forces on an object travelling at terminal velocity
-Forces are balanced in vertical and horizontal components
-No resultant force, therefore no acceleration
Define terminal velocity
Maximum speed of an object
What is the acceleration at terminal velocity?
0ms^-2
Define Newton’s 3rd Law
Every action has an equal and opposite reaction. This means that there is always a pair of forces acting on interacting objects
Define moment
Turning effect of a force
What distance is used to calculate a moment?
Perpendicular distance between the line of action of the force and the axis of rotation
Define the principle of moments
For an object to be in equilibrium, sum of clockwise moments = sum of anticlockwise moments
What is an object’s centre of gravity?
The single point through which the object’s entire weight can be said to act
What will occur if the line of action an object’s center of gravity lies outside its base?
The object’s weight will produce a resultant moment and so if it’s unsupported, the object may fall
What is true for projectiles?
-Time is constant for horizontal/vertical
-a=0 for horizontal
