Andy has a remote-controlled car which he uses primarily to annoy the family cat. He has found that the cat’s annoyance is maximized for motion which can be parametrized as x(t) = 0.5t^3 – 3t, where x is in meters and t is in seconds. Calculate the position at t=3.1s in meters. Calculate the acceleration at t=2.3s (m/s2). At what time is the instantaneous velocity zero?

Zeros that follow non-zeros numbers and are also to the right of a decimal point are significant

The long handle on a rake is a(n) a. lever b. screw c. wedge d. inclined plane

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?