Askateboarder on a half-pipe changes his velocity from 6.0 m/s forwards to 4.0 m/s backward in 5.0 s. what is the acceleration of the skateboarder?

The transfer of heat through the movement of a gas or liquid a. convection b. conduction c. radiation

What’s #16 asking me and how do i solve it?

The magnitude of the amount of energy released by burning a fuel source, measured in energy per unit mass, is called its fuel value. note that the fuel value is the negative of the isobaric specific heat of combustion for the fuel. if all the energy obtained from burning 1.23 pounds of butane with a fuel value of 10.85 kcal/g is used to heat 128.0 kg of water at an initial temperature of 18.3 °c, what is the final temperature? note that 1 lb = 453.6 g.