Arubber ball is dropped from rest from a height h. the ball bounces off the floor and reaches a height of 2h/3. how can we use the principle of the conservation of mechanical energy to interpret this observation?

a) during the collision with the floor, the floor did not push hard enough on the ball for it to reach its original height.

b) some of the ball’s potential energy was lost in accelerating it toward the floor.

c) the force of the earth’s gravity on the ball prevented it from returning to its original height.

d) work was done on the ball by the gravitational force that reduced the ball’s kinetic energy.

e) work was done on the ball by non-conservative forces that resulted in the ball having less total mechanical energy after the bounce.

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If a refrigerator is a heat pump that follows the first law of thermodynamics, how much heat was removed from food inside of the refrigerator if it released 380j of energy to the room?

Clothing made of several thin layers of fabric with trapped air in between, often called ski clothing, is commonly used in cold climates because it is light, fashionable, and a very effective thermal insulator. so it is no surprise that such clothing has largely replaced thickand heavy old-fashioned coats. (a) consider a jacket made of five layers of 0.1-mm-thick synthetic fabric (k = 0.13 w/m·°c) with 1.5-mm-thick air space (k = 0.026 w/m·°c) between the layers. assuming the inner surface temperature of the jacket to be 28°c and the surface area to be 1.25 m2, determine the rate of heat loss through the jacket when the temperature of the outdoors is 0°c and the heat transfer coefficient at the outer surface is 25 w/m2·°c. (b) what would your response be if the jacket is made of a single layer of 0.5-mm-thick synthetic fabric? what should be the thickness of a wool fabric (k = 0.035 w/m·°c) if the person is to achieve the same level of thermal comfort wearing a thick wool coat instead of a five-layer ski jacket?

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.