A 65.25 kg person holding a steel ball stands motionless on a frozen lake. The person then throws the ball, which propels the person at 1.25 m/s to the
right and the ball 4.05 m/s to the left. If the initial momentum of the system is
zero, what is the mass of the steel ball?
O A. 4.03 kg
B. 16.11 kg
OC. 20.14 kg
D. 3.24 kg

The passing of heat through a material while the material itself stays in place. a. radiation b. conduction c. convection

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)