29. On February 15, 2013, a superbolide meteor (brighter than the Sun) entered Earth’s atmosphere over Chelyabinsk, Russia, and exploded at an altitude of 23.5km. Eyewitnesses could feel the intense heat from the fireball, and the blast wave from the explosion blew out windows in buildings. The blast wave took approximately 2minutes 30 seconds to reach ground level. (a) What was the average velocity of the blast wave? b) Compare this with the speed of sound, which is 343 m/s at sea level.
35. A particle moves along the x-axis according to x(t) = 10 m/s ∙ t – 2 m/s2 ∙ t2.
(a) What is the instantaneous velocity at t = 2 s and t = 3 s?
(b) What is the instantaneous speed at these times?
(c) What is the average velocity between t = 2 s and t = 3 s?
41. Assume an intercontinental ballistic missile goes from rest to a suborbital speed of 6.50 km/s in 60.0 s (the actual speed and time are classified). What is its average acceleration in meters per second and in multiples of g (9.80 m/s2)?
42. An airplane, starting from rest, moves down the runway at constant acceleration for 18 s and then takes off at a speed of 60 m/s. What is the average acceleration of the plane?
45. A particle moves in a straight line with an initial velocity of 30 m/s and constant acceleration 30 m/s2.
(a)What is its displacement at t = 5 s?
(b) What is its velocity at this same time?
51. A bullet in a gun is accelerated from the firing chamber to the end of the barrel at an average rate of 6.20 × 105m/s2for 8.10 × 10-4s. What is its muzzle velocity (that is, its final velocity)?
68. A basketball referee tosses the ball straight up for the starting tip-off. At what velocity must a basketball player leave the ground to rise 1.25 m above the floor in an attempt to get the ball?
No comments:
Post a Comment