Using physics to make things work Flashcards
What is the centre of mass of an object?
The point at which the mass of an object may be thought to be concentrated.
True or false, if freely suspended an object will come to rest with its centre of mass above the point of suspension.
False, it will come to rest with its centre of mass directly below the point of suspension.
The centre of mass of a symmetrical object is always…
…along the object’s line of symmetry.
Equation for a simple pendulum:
T = 1/f
Where:
T is time in s
f is frequency in Hz
Factor which the time period of a pendulum depends upon:
Length of pendulum.
Define a moment.
The turning effect of a force.
Equation for moments:
M = F x d
Where:
M is moment in Nm
F is force in N
d is distance in m
If an object is not turning what can be true about the moments?
The total clockwise moment is equal to the total anticlockwise moment about the pivot.
What happens when the line of action from the centre of mass of an object lies outside the base of the object?
It will topple.
What happens when the line of action from the centre of mass of an object lies inside the base of the object?
It will fall back to the base.
True or false, liquids are compressible.
False, liquids are virtually incompressible.
Force of a liquid is transmitted…
…equally in all directions.
Hydraulic systems can be used as force multipliers, how?
Use of different cross-sectional areas on the effort and load sides.
Equation for pressure:
P = F/A
Where:
P is pressure in Pa
F is force in N
A is cross-sectional area in m2
When an object moves at a constant speed in a circular motion its what is constantly changing?
Its acceleration and velocity as velocity is speed with direction. The object’s direction is constantly changing so it is constantly acceleration.
