Which state can a substance NOT be in if heat transfer through convection is occurring?

A kettle requires 2400 Coulombs of charge to pass through its heating element, with a resistance of 6 Ohms, in a time of 200 seconds in order to boil the water inside it. Calculate the current flowing and the power of the kettle.

Insulating a home costs £2000 and saves £50 a year. What is the payback time?

If a motor uses 500J to raise a box of 25N, how high has the box been lifted?

I throw a ball straight up with an initial velocity of 2m/s. How high is it after a fifth of a second?