Design a 1200-W electric hair dryer such that the air temperature and velocity in the dryer will not exceed 50°C and 3 m/s, respectively.

A cylindrical resistor element on a circuit board dissipates 0.15 W of power in an environment at 40°C. The resistor is 1.2 cm long, and has a diameter of 0.3 cm. Assuming heat to be transferred uniformly from all surfaces, determine the amount of heat this resistor dissipates during a 24 h period;

An immersion heater used to boil water for a single cup of tea plugs into a 120 V outlet and is rated at 300 W. Suppose your super-size, super-insulated tea mug contains 400 g of water at a temperature of 13 ●C. You can ignore the energy needed to raise the temperature of the mug and the heater itself. 1)What is the resistance of the heater?

2 part question.

QUESTION 2 Which of the following is an accurate statement? O A. It is possible to add a scalar quantity to a vector. O B. Even though two vectors have unequal magnitudes, it is possible that their vector sum is zero. OC. Rotating a vector about an axis passing through the tip of the vector does not change the vector. OD. The magnitude of a vector is independent of the coordinate system used. O E. The magnitude of a vector can be zero even though one of its components is not zero.

On a February night, energy leaves a house by several energy leaks, including 1.50×103W by conduction through the ceiling, 450W by infiltration (airflow) around the windows, 140W by conduction through the basement wall above the foundation sill, and 40.0W by conduction through the plywood door to the attic. To produce the biggest saving in heating bills, which one of these energy transfers should be reduced first? Explain how you decide.

#20

In the figure, a resistance coil, wired to an external battery, is placed inside a thermally insulated cylinder fitted with a frictionless piston and containing an ideal gas. A current i = 220 mA flows through the coil, which has a resistance R = 560 0. At what speed v must the piston, of mass m = 17.0 kg, move upward in order that the temperature of the gas remains unchanged? Number i Units

An office worker uses an immersion heater to warm 250 g of water in a light, covered, insulated cup from 20.0°C to 100°C in 4.00 min. The heater is a Nichrome resistance wire connected to a 120-V power supply. Assume the wire is at 1008C throughout the 4.00-min time interval. (a) Specify a relationship between a diameter and a length that the wire can have. (b) Can it be made from less than 0.500 cm3 of Nichrome?

A window air conditioner is placed on a table inside a well-insulated apartment, plugged in and turned on. What happens to the average temperature of the apartment? (a) It increases. (b) It decreases. (c) It remains constant. (d) It increases until the unit warms up and then decreases. (e) The answer depends on the initial temperature of the apartment.