Calculating Acceleration and Tension in Vertical Circular Motion

[rachael]

7 A body of mass 0.40 kg is whirled in a vertical circle on
the end of a cord of length 0.40 m. If the tension in the
cord is 0.80 N when the body is at its highest point,
find:

b the acceleration and the speed of the mass at the
lowest point
c the tension in the cord at the lowest point.

How would you find the velocity for part b?
Would you use mv^2/r=F-mg if not what do i use?
for part c what do i use to find the tension at the lowest point?Do i use the same formula as well for b?

 

[Hootenanny]

Yes, you can work out the net force acting (which will always be towards the centre of the circle) and then apply Newton's law.
For part c you already know the centripetal force (you would have worked it out in a), then draw a diagram of all the forces acting when the body is at the bottom of the circle.

 

[rachael]

thank you...