Back(II) A rocket with a mass of 2.45 x 106 kg is launched by exerting a vertical force of 3.55 x 107 N on the gases it expels. Determine the acceleration of the rocket, Assume g remains constant, and ignore the mass of gas expelled (not realistic).
A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.75 of her regular weight. Calculate the acceleration of the elevator, and find the direction of acceleration.
What will a spring scale read for the weight of a 58.0‑kg woman in an elevator that moves upward with constant speed 4.4 m/s?
(II) What will a spring scale read for the weight of a 58.0‑kg woman in an elevator that moves downward with constant speed 4.4 m/s?
(II) What will a spring scale read for the weight of a 58.0‑kg woman in an elevator that moves with a downward acceleration 0.18 g?
(II) An exceptional standing jump would raise a person 0.80 m off the ground. To do this, what force must a 68-kg person exert against the ground? Assume the person crouches a distance of 0.20 m prior to jumping, and thus the upward force has this distance to act over before he leaves the ground.
(II) What will a spring scale read for the weight of a 58.0‑kg woman in an elevator that moves in free fall?
(II) An 18.0-kg monkey hangs from a cord suspended from the ceiling of an elevator. The cord can withstand a tension of 215 N and breaks as the elevator accelerates. What was the elevator's minimum acceleration (magnitude and direction)?
An inclined plane, fixed to the inside of an elevator, makes a 38° angle with the floor. A mass m slides on the plane without friction. What is its acceleration relative to the plane if the elevator accelerates downward at 0.50 g?
Determine a formula for the acceleration of the system shown in Fig. 4–49 (see Problem 55) if the cord has a non-negligible mass mC. Specify in terms of ℓA and ℓB , the lengths of cord from the respective masses to the pulley. (The total cord length is ℓA + ℓB.)
High-speed elevators function under two limitations: (1) the maximum magnitude of vertical acceleration that a typical human body can experience without discomfort is about 1.2 m/s2, and (2) the typical maximum speed attainable is about 9.0 m/s. You board an elevator on a skyscraper's ground floor and are transported 180 m above the ground level in three steps: acceleration of magnitude 1.2m/s2 from rest to 9.0 m/s, followed by constant upward velocity of 9.0 m/s, then deceleration of magnitude 1.2m/s2 from 9.0 m/s to rest. Determine the elapsed time for each of these 3 stages.
An inclined plane, fixed to the inside of an elevator, makes a 38° angle with the floor. A mass m slides on the plane without friction. What is its acceleration relative to the plane if the elevator moves upward at constant speed?
(II) A narrow but solid spool of thread has radius R and mass M. If you pull up on the thread so that the cm of the spool remains suspended in the air at the same place as it unwinds, what force must you exert on the thread?
(II) How much tension must a cable withstand if it is used to accelerate a 1400-kg car vertically upward at 0.70m/s2?
(III) An object moving vertically has at t = 0. Determine a formula for its velocity as a function of time assuming a resistive force F = -bv as well as gravity for two cases: is downward.