A 1210 kg rollercoaster car is moving 7.33 m/s. As it
approaches the station, brakes
slow it down to 1.88 m/s over a
distance of 5.29 m. How much
work did the brakes do?

Iwill give 30 points to whoever answers ! what is the formula for actual mechanical advantage and ideal mechanical advantage?

Which of the following changes will result in a stronger electromagnet? a. using fewer coils of wire b. using a higher voltage c. using a shorter nail d. using a longer wire

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?