You are relaxing at home, working on your coin collection. you have learned that collectible coins are sometimes plated with gold to enhance their beauty and value. on an online site that sells collectible coins, you see a commemorative quarter-dollar advertised for sale at $4.98. the information on the site says that the coin has a diameter of 24.6 mm and a thickness of 2.10 mm, and it is completely covered with a layer of pure gold 0.175 μm thick. you know that gold scheme by which you would separate the gold from the base coin and sell the gold at the current market price. you begin your scheme by buying the advertsed coin at $4.98 (assume the density of gold is 19.3 g/cm3) is a valuable asset and you come up with a (a) what is the value of the gold for a single such coin (in cents)? assume that the price of gold is $38.00 per gram (b) what i1? what would be the cost (in dollars) of the gold to produce the coin if the coin were made entirely of gold?

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.

Awater-filled u-tube manometer is used to measure the pressure inside a tank that contains air. the water level in the u-tube on the side that connects to the tank is 5 ft above the base of the tank. the water level in the other side of the u-tube (which is open to the atmosphere) is 2 ft above the base. determine the pressure within the tank.

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?