A hot plane surface at 100°C is exposed to air at 25°C with a combined heat transfer coefficient of 20W/m2*K The heat loss from the surface is to be reduced by half by covering it with sufficient insulation with a thermal conductivity of 0.1 W/m*K. Assuming the heat transfer coefficient to remain constant, the required thickness of insulation is

(a) 0.1cm
(b) 0.5 cm
(c) 1.0 cm
(d) 2.0 cm
(e) 5 cm

Sarah and michelle work at a tech company that designs exercise apps. sarah tells michelle she has heard that james, their supervisor, interviewed with a competitor and may be leaving the company, which would open up a management position. what kind of power is sarah exerting?

For problems 1-3, consider a simple dc brush motor with a permanent magnet stator. with an an consider a simple dc brush motor with a permanent magnet ae supply voltage of 100 v, the no-load speed of the motor is 1000 rpm. this motor can provide a torque of 1.9 n-m at 800 rpm drawing a current of 2 a current are both zero at no load.) 1. with an armature supply voltage of 100 v, the motor is operated at 900 rpm. what is the motor torque? what is the mechanical power delivered by the motor? what is the current draw? what is the electrical power input? what is the energy efficiency of the motor? with an armature supply voltage of 100 v, the motor is operated at 1100 rpm (where it acts as a generator). what torque input is required? what mechanical power is required what current is generated? what is the electrical power generated? what is the energy efficiency of the motor acting as a generator? 2. with an armature supply voltage raised to 120 v, the motor is operated at 1000 rpm. what is the no-load speed? what is the motor torque? what is the mechanical power delivered by the motor? what is the current draw? what is the electrical power input what is the energy efficiency of the motor? 3.

What is the momentum of a 2 kg object moving at 15 meters per second