Jenny (mass = 63 kg) is skiing down a 17° slope. A tailwind is assisting her as she travels down the slow with a force of 18 N (parallel to the slope). The coefficient of dynamic friction between Jenny’s skis and the snow is 0.04. Assuming the ski hill is perfectly smooth and the net force in the vertical (y) direction is zero, what is the resultant (net) external force acting on Jenny and what is her acceleration? Include a free body diagram to illustrate the scenario, show complete workings, and report answers to two (2) decimals (with units and direction as required).

We want to calculate the total metabolic heat generated by a singing canary taking into account heat transfer by radiation, convection and exhaling air. the air temperature is 20 oc, canary’s body internal and surface temperature is 33oc, external body surface convective heat transfer coefficient is 25.2 w/m2 .k, temperature difference between the inhaled and exhaled air is 4.3 oc, the ventilation rate is 0.74 cc of air per second, specific heat of air is 1.0066 kj/kg.k and density of air is 1.16 kg/m3 . assume the canary’s body to be a cylinder with 7 cm diameter and 9 cm length, and heat exchange is from the side as well as the top and bottom of cylinder. calculate 1) the net rate of heat lost by radiation, assuming heat gained by the bird through radiation from the surroundings is 11.5 w; 2) rate of heat transferred by convection to the surrounding air; 3) rate of heat transferred in the exhaling air without considering any internal evaporation; 4) total metabolic power.

Does work output exceed work input when a machine is used? a) yes, it does, as machines create energy. b) it depends on the type of machine used. c) no, it doesn’t, as machines are inefficient. d) no, it doesn’t, as machines cannot create energy.

How do we measure or think of speed in the united states?