P1.5 Flashcards
(14 cards)
What can a force do
Can change the size, shape and motion
What does friction do
Creates heats and resistance to movement
Does friction act on an object moving through a liquid? Yes or No?
Yes
Does friction act on an object moving through a gas? Yes or no? And what type of friction
Yes and air resistance
Objects either remain at rest or move in a constant speed unless …
There is a resultant force on the object
What is F=ma
Force = mass x acceleration
What is the equation for the spring constant
k=F/x
where k = spring constant in Nm-1
x = extension length in m
F = restoring force in N
Or
Fg = Fx
mg = kx
k = mg/x
Which is mass x acceleration due to gravity divided by extension length in metres
What is the limit of proportionality
The limit of proportionality is the point beyond which a material no longer stretches or compresses in a straight-line relationship. After this point, the material may start to deform permanently and does not follow Hooke’s law.
What is the moment of a force (torque)
Torque is a measure of how much a force causes an object to rotate
What is the equation for the moment (torque)
Force x perpendicular distance
τ = Fd⊥
When there is no resultant force and no resultant moment (torque) …
the object is at equilibrium
What is the centre of gravity
A point where an object’s weight is evenly distributed in all directions
How can you find the centre of gravity
Suspend a weight over the object and draw a line of the string going down the object. Repeat this process in different positions and the point of intersection is the centre of gravity
What does a lower centre of gravity do
Lower center of gravity, the more stable the object is
