Download Physics Problems: Skate Speed, Graph Area, Particle Motion, Centrifuge, Falling Balls, Bra and more Exams Physics in PDF only on Docsity! 1. A skateboarder rides in a straight line along a smooth, level street at a steady speed of 7.0 m/s for 20 s, then encounters a rough patch of pavement 40 m long that takes him 15 seconds to skate over. What was his approximate average speed (magnitude of velocity) for the entire straight line skate? a) 4.7 m/s b) 6.0 m/s c) 5.5m/s * d) 5.1 m/s e) none of these are even approximately correct 2. The area under a certain graph gives information about the change in the velocity of a certain moving object. The slope of that graph does not yield particularly useful kinematic information. The graph is most likely a) x-component versus y-component of position b) position versus time c) velocity versus time * d) acceleration versus time e) none of these are even approximately correct 3. A moving particle is experiencing an acceleration whose magnitude is non-zero and constant, yet the speed (magnitude of velocity) of the particle is not changing. What can you say about the motion of this particle? a) it is in free fall b) it is at rest * c) it is moving in a circular path d) it is moving in a parabolic path e) none of the above are possible 4. In a centrifuge used to train astronauts, the trainee is seated in a gondola at the end of an 10 meter long boom. It is desired to simulate the re-entry acceleration of 9 "g's" that the astronaut might encounter. Approximately how much time will be required for each revolution of the centrifuge? Recall that "g" is the magnitude of the Earth's free-fall gravitational acceleration. a) 2.9 s * b) 2.1 s c) 1.4 s d) 0.47 s e) none of the above are even approximately correct x t x t x t x t x t 5. A ball was dropped, from rest, vertically downward from the roof of a tall building. A short time later an identical ball was thrown downward from the same spot as the first ball. The two balls struck the pavement below at the same instant. Neglecting any air resistance, which of the following is a true statement? a) during their free-fall intervals, the velocities of the two balls each changed by the same amount * b) during their free-fall intervals, both balls had the same acceleration c) during their free-fall intervals, both balls had the same average velocity d) only (a) and (b) are true e) only (b) and (c) are true 6. An automobile travelling at a speed of 28 m/s along a straight level road brakes smoothly and uniformly to a stop, requiring an elapsed time of 5.5 s to come to rest. Assuming that the positive direction is taken as "forward" for the car, which graph below most properly represents the position of the car as a function of time? (a) * (b) (c) (d) (e) 7. How far did the car in the question above travel while braking to a stop? a) 154 m b) 116 m c) 40 m d) 5 m * e) none of the above are even approximately correct
