Two objects in physical contact with each other are in thermal equilibrium.      Which of the following statements must be true about the objects?   They have the same temperature.      More than one of these choices is true      None of these choices are true.      There is no net heat transfer between them.

In an effort to stay awake for an all-night study session, a student makes a cup of coffee by first placing a 200 W electric immersion heater in 0.400 kg of water. How much heat must be added to the water to raise its temperature from 21.0°C to 77.0°C? Express your answer in joules. IVE ΑΣΦ Q = Submit Part B t = Request Answer Submit How much time is required? Assume that all of the heater's power goes into heating the water. Express your answer in seconds. OF 15. ΑΣΦ ? Request Answer J ? S Re

A 1.17 kg hammer strikes a 20 g brass nail into a wood board. The nail is horizontally aligned and at the moment of impact with the nail, the hammer had a speed of 9.1 m/s. Assume both the hammer and the nail come to a stop and that all of the thermal energy generated goes into heating the nail. Determine how much the temperature of the nail will increase after one hit and how many hits it will take to increase its temperature 88°C ΔT after one hit = Minimum number of hits needed to increase the temperature by at least 88°C =

A 0.100 kg piece of ice at initial temperature −5.00 ◦C is placed in a perfectly insulated container with 1.00 kg (1 L) of water at initial temperature 20.0 ◦C. The container absorbs or releases no heat. All of the ice melts as the system reaches an equilibrium temperature Tf .  How much heat must the ice exchange with the rest of the system to raise its temperature to the melting point, 0.00 ◦C? Would this heat exchanged be positive, zero, or negative? Once the ice reaches its melting point, how much heat must the ice exchange with the rest of the system to melt? Would this heat exchanged be positive, zero, or negative? Once the ice melts, it is liquid water at 0.00 ◦C. Write an expression for the heat exchanged by the newly-melted ice QI to reach the equilibrium temperature Tf . Would you expect QI to be positive, zero, or negative? Write an expression for the heat exchanged by the original water QW to reach the equilibrium temperature Tf from its initial temperature. Assuming no…