Topic 9 Forces Around You Flashcards
What is Newton’s first law of motion?
An object remains at rest or moves in a straight line at constant speed unless it is acted on by an unbalanced force
How do you calculate speed?
Distance / time
What is the abbreviated for speed?
v
What is the abbreviated for distance?
d
What is the abbreviated for time?
t
What is an unbalanced force?
It is a single force that is applied to an object to change its direction
If two forces are applied to opposite direction of an object what is this called?
Balanced force - this is usually of equal strength
Define equilibrium
Any object that is subject to balanced forces is said to be in equilibrium
In terms of equilibrium if an object stays at rest what is this called?
Static equilibrium
Any object that is subjected to balanced forces
In terms of equilibrium if an object is moving at constant speed, what is this called?
Dynamic equilibrium
Any object that is subjected to balanced forces
How do you calculate weight?
weight = mass × acceleration due to gravity
How can this be written using symbols?
W = m × g or W = mg
What is the abbreviated for weight?
W
What is the abbreviated for mass?
m
What is the abbreviated for gravity
g
When symbols are written next to each other what does this imply?
They should be multiplied
e.g.
W = mg
Close to the earths surface what is the value of gravity?
9.81 m s−2
for less precise calculations you can use 10 m s−2.
What is mass?
Mass is a measure of how much matter an object is made of
What is weight?
weight is the force that our planet exerts on that matter.
weight is a force, it also has a direction, so we have to say that the weight of an object is W = mg downwards
Is it correct to say ‘My weight is 90 kg’?
we say ‘My weight is 90 kg’, but the correct statement is ‘My mass is 90 kg’. Since weight is a force, it also has a direction, so we have to say that the weight of an object is W = mg downwards
What is the value of a newton?
1 kg m s−2
What is the abbreviation of a newton?
N
