Section 5: Mechanics Flashcards
What’s the difference between a scalar and a vector?
A scalar quantity has only size, while a vector quantity has size and direction.
What name is given to a vector formed by adding vectors together?
The resultant vector
Give an example of 3 vectors.
Displacement, velocity, force, acceleration or momentum
Give an example of 3 scalars.
Any 3 from: length, distance, speed, mass, temperature, time or energy
If a body is in equilibrium, what’s the sum of all the forces acting on it?
0
Explain what equilibrium means in the context of a moving object
The sum of all the forces acting on a body in equilibrium is 0
What is a moment?
A moment is the turning effect of a force around a turning point.
What name is given to a pair of forces of equal size which act parallel to each other, in opposite directions?
A couple
What is the centre of mass of an object?
The centre of mass of an object is the single point that you can consider its whole weight to act through
Where is the centre of mass in a uniform regular solid
At the centre of an object
What’s the velocity of an object?
The rate of change of displacement
What’s the acceleration of an object?
The rat of change of velocity
What does SUVAT stand for? Give the units for each measurement.
S- Displacement (in m) U- Initial Velocity (in ms^-1) V- Final Velocity (in ms^-1) A- Acceleration (in msˉ²) T- Time (in s)
What kind of motion does a curved displacement-time graph show?
Acceleration or deceleration
What kind of motion does a straight line show on a displacement-time graph?
Constant velocity
What does the rate of change of gradient on a displacement-time graph represent?
Distance
How would you calculate the average velocity of a moving object with non-uniform acceleration using a displacement-time graph?
Divide the overall change in displacement by the time taken
What is the difference between average and instantaneous velocity?
Instantaneous velocity is an object’s velocity at a particular moment in time, average velocity is the overall displacement divided by time taken
What does the gradient of a velocity-time graph tell you?
Acceleration
How is uniform acceleration shown on a velocity-time graph?
A straight line
What does the area under a velocity-time graph tell you?
The displacement
How is non-uniform acceleration shown on a velocity-time graph?
A curved line
How would you find velocity from an acceleration-time graph?
The area under the graph
How would constant velocity appear on an acceleration-time graph?
Constant velocity means acceleration is zero, so it would appear as a straight horizontal line through 0 on the vertical axis.