An object is moving with a speed of 35 m/s and has a kinetic energy of 1500 J, what is the mass of the object?

You'd use the equation kinetic energy=mass*0.5*speed^2

So you'd rearrange this to get mass = kinetic energy / 0.5 * speed^2

Which is mass = 1500J/0.5*35^2

=2.44897959183673469 ... kg