Circular motion U4 Flashcards
W=
Theta/t
2(pie)f
2(pie)/t
F=
mv^2/r
V=
S/t
r(theta)/t
rW
2(pie)r/t
a=
V^2/r
rW^2
P=
Fv
Define 1 radian
When the radius and arc length of a sector are equal
Define angular displacement (W)
Vector measurement of the angle through which something has turned
Define angular velocity
The rate at which the angular displacement changes
What should the graph of W^2/F look like and why does it?
It should have a straight line of best fit
Because F=mrW^2 and
W^2=F/mr
(Gradient=1/mr)
What is an experiment to investigate centripetal force
Spinning a rubber bung on a string in a circle.
Describe the centripetal force experiment stating what needs to be measured and how to measure it
Spinning the rubber bung on a string in a circle causes tension in the string to act towards the centre acting as the centripetal force. Mark the string with a paper clip underneath so that the radius will remain constant and more easily measured; measure the mass of the bung and then time 10 revolutions of the bung on the string then do 2 repeats if neccassary and find an accurate value for the time for one revolution. This time is the angular velocity (W). You can either change the mass on the strong and therefore the force or change the radius to find different values of W to be plotted on a W^2/F graph.
Why, in the centripetal force investigation do you plot W^2 against F and not W?
Because of the equation F=mrW^2 : W^2=F/mr :y=mx+c : y=mx (c=0) : so y=W^2, m=1/mr and x=F
How can centripetal be increased?
Increase in mass
Faster rotation
Smaller radius
Why does centripetal acceleration require a resultant force
Newtons1st law says that there is only acceleration ONLY when there is a resultant force acting so therefore the centripetal acceleration requires a resultant force.
Why do objects travelling in a circular path accelerate
When an object travels in a circular path the direction is constantly changing therefore the velocity is changing too. If velocity changes then there is acceleration…
