Stuck on OCR Physics A2 Question about Gravity

Hi Guys,

I am having trouble with a question in the A2 OCR Physics A text book. If you have it it is on page 37.

I am stuck on question 3 which is:

The space shuttle orbits the Earth at a height of 4.0x10⁵m above the surface. The kinetic energy of the shuttle in this orbit is 2.8x10¹²J. Calculate:
a. the force of gravity on the shuttle
b. the gravitational field strength at this height
c. the mass of the space shuttle

I have tired to use a few different equations, but can't seem to figure it out, any ideas?

Thanks!
Ben.

So you know that the force on an object in a circular orbit is $F=mv^2/r$ in the radial direction.
What does the numerator of this look similar to?

Ooh, thats great thank you, I had completely forgotten about this formula!