A 4-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

12kWhr

Explanation:

Energy = Power * Time

Power = 4kW

Time = 3hrs

Substitute into the formula

Energy used up = 4kW * 3hrs

Energy used up = 12kWhr

d. platinum would have the greatest temperature increase because it has the lowest specific heat.

initial speed when it is dropped is 150 ft/s

now at the same moment the acceleration due to gravity is perpendicular to its velocity

so as we know that

now we have centripetal acceleration a = 32 ft/s^2 as its perpendicular to velocity

while tangential acceleration at the same moment will be zero

so

now radius of curvature is given as

so the radius of curvature just after it is dropped is 703.125 ft