Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
|
What is the centre of mass of an object?
|
The point where all it's mass can be thought to be concentrated |
|
|
Where is the centre of mass of an object when it is suspended in equilibrium?
|
It's centre of mass is directly beneath the point of suspension |
|
|
Where is the centre of mass for a symmetrical object?
|
Along the axis of symmetry |
|
|
How do you find the centre of mass of a thin irregular sheet of material?
|
Suspend the material from a pin held in a clamp stand. When it comes to rest, hand a plumb line from the same pin. Mark the position of the plumb line against the sheet. Hang the sheet with the pin at another point and repeat the procedure. The centre of mass is where the lines marking the position of the plumb line cross. |
|
|
What sort of motion is a simple pendulum an example of?
|
Oscillating motion |
|
|
What is the amplitude of the oscillation for a simple pendulum?
|
The distance from the equilibrium position to the highest position on either side. |
|
|
What is the frequency of oscillations for a simple pendulum?
|
The number of complete cycles per second. |
|
|
What is the time period of the oscillation for a simple pendulum?
|
The time taken for one complete cycle.
|
|
|
How would you measure the time period of a pendulum? |
Measure the average time for 20 oscillations and divide them by 20. |
|
|
What does the time period of a pendulum depend on? |
The length of the pendulum. The longer the pendulum the longer the time period. |
|
|
T = 1 / f |
Time period (s) = 1 / frequency (Hz) |
|
|
What is the turning effect of force called? |
It's moment
|
|
|
M = F x d |
Moment (Nm) = Force (N) x Perpendicular distance from the line of action of the force to the pivot (m) |
|
|
How would you increase the moment?
|
increase the force and/ or increase the distance from the pivot. |
|
|
What does a lever act as, regarding force?
|
A force manipulator |
|
|
What happens, regarding moments, for an object that is not turning?
|
The sum of the anticlockwise moments = the sum of the clockwise moments |
|
|
What do you need to know to be able to calculate the force needed to stop an object turning?
|
All of the forces that don't act through the pivot and their perpendicular distances from the line of action to that point. |
|
|
Where does the line of the action of the weight of an object act through?
|
It's centre of mass |
|
|
What happens if the line of the action of the weight lies outside the base of an object?
|
There will be a resultant moment and the object will tend to topple over. |
|
|
What is the stability of an object increased by? |
Making it's base as wide as possible and making it's centre of mass as low as possible |
|
|
What is centripetal acceleration?
|
The velocity of an object moving in a circle at a constant speed is continually changing because the object's direction is continually changing and therefore it is accelerating. |
|
|
What force causes centripetal acceleration?
|
Centripetal force |
|
|
In which direction does centripetal force act? |
Towards the centre of the circle |
|
|
What would happen to an object moving around a circle if the centripetal force stopped acting?
|
The object would continue to move in a straight line at a tangent to the circle? |
|
|
What would increase the centripetal force needed to act on an object? |
An increase in the object's mass. An increase in the speed of the object. A decrease in the radius of the circle.
|
|
|
What is the unit for pressure?
|
The Pascal (Pa)
|
|
|
P = F / A
|
Pressure (Pa) = Force (N) / cross-sectional area (m squared) |
|
|
What does a hydraulic pressure system do?
|
It uses fluid to exert a force |
|
|
What does the force exerted by a hydraulic pressure system depend on? |
The force exerted on the system. The area of the cylinder which this force acts on. The area of the cylinder that exerts the force.
|
|
|
When can a hydraulic pressure system be used as a force multiplier?
|
When the cross-sectional areas on the load side and the effort side are different.
|
