A skydiver jumps from a flying plane. his height from earth is given through formula h=400+3t-4.9t^2. 1. in which moment the velocity is 46m/s?

2. find the momentum acceleration

Now I've solved it but I'm not sure whether I found it correctly or not.
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An athlete swings a ball, connected to the end of a chain, in a horizontal circle. the athlete is able to rotate the ball at the rate of 8.13 rev/s when the length of the chain is 0.600 m. when he increases the length to 0.900 m, he is able to rotate the ball only 6.04 rev/s. (a) which rate of rotation gives the greater speed for the ball? 6.04 rev/s 8.13 rev/s (b) what is the centripetal acceleration of the ball at 8.13 rev/s? m/s2 (c) what is the centripetal acceleration at 6.04 rev/s? m/s2

Which wave is the result of amplification and produces a louder sound

Which type of energy is transferred by convection currents?