Part A ReviewI Constants Periodic Table In researching the forces that act on flying birds scientists studied the motion of cockatiels' bodies as they fly in horizontal flight. As the birds beat their wings, their bodies move up and down. (Figure 1) shows the vertical acceleration of a cockatiel's body during one wing beat, consisting of an upstroke followed by a downstroke If the bird's mass is 82 g, what is the maximum net vertical force exerted on the bird? Express your answer with the appropriate units. F-2.95 SubmitPn Previous Answers Request Answer X Incorrect; Try Again; 5 attempts remaining Figure 1 of 1 Part B "y (m/s2) 50 The bird is held in level flight due to the force exerted on it by the air as the bird beats its wings. What is the maximum value of this force due to the air? Note that the bird's weight, the force of gravity acting on it, is calculated using w mg, a result that will be justified in Chapter 5 Express your answer with the appropriate units. 0 I-t (s) 0.02 0.06 0.08 0.10 50 (FairxValue Units Upstroke Downstroke Submit Request Answer

At a circus, a donkey pulls on a sled carrying a small clown with a force given by . A horse pulls on the same sled, aiding the hapless donkey, with a force of The mass of the sled is 575 kg. Using and from for the answer to each problem, find (a) the net force on the sled when the two animals act together, (b) the acceleration of the sled, and (c) the velocity after 6.50 s.

Astronauts in orbit are apparently weightless. This means that a clever method of measuring the mass of astronauts is needed to monitor their mass gains or losses, and adjust their diet. One way to do this is to exert a known force on an astronaut and measure the acceleration produced. Suppose a net external force of 50.0 N is exerted, and an astronaut’s acceleration is measured to be 0.893m/s2 . (a) Calculate her mass. (b) By exerting a force on the astronaut, the vehicle in which she orbits experiences an equal and opposite force. Use this knowledge to find an equation for the acceleration of the system (astronaut and spaceship) that would be measured by a nearby observer. (c) Discuss how this would affect the measurement of the astronaut’s acceleration. Propose a method by which recoil of the vehicle is avoided.

Mixed-pair ice skaters performing in a show are standing motionless at arms length just before starting a routine. They reach out, clasp hands, and pull themselves together by only using their arms. Assuming there is no friction between the blades of their skates and the ice, what is their velocity after their bodies meet?