find the time taken for the first stone to hit the water.
x=u*t+1/2*a*t^2 where u=0ms^-1
then use that value to find time for the second stone. t2=(t1-1)
finally use this same equation again to find u.
x=u*t+1/2*a*t^2
you only need to go up to a third of the number. This is because if it is even then you know it is not prime, unless it is two. odd numbers are not divisble by 2, so the next divisor would be 3.
The answer is A. Use the right hand rule, with the magnetic field going perpendicular to the wire, out from the magnet (out from the centre of the circle), and you use the force opposing motion. When you do this, you will get the induced current going counter clockwise around the ring from the...
A worked solution
The attached document has a worked solution to your problem. The fundamental theorem of calculus makes more sense if you think of integrals as anti-derivatives, as they were first taught to me.