6. Intro to Forces (Dynamics)

A woman has a mass of 55 kg. What is her weight while standing on earth?

It takes the elevator in a skyscraper 4.0 s to reach its cruising speed of 10 m/s. A 60 kg passenger gets aboard on the ground floor. What is the passenger's weight after the elevator reaches its cruising speed?

It takes the elevator in a skyscraper 4.0 s to reach its cruising speed of 10 m/s. A 60 kg passenger gets aboard on the ground floor. What is the passenger's weight before the elevator starts moving?

Zach, whose mass is 80 kg, is in an elevator descending at 10 m/s. The elevator takes 3.0 s to brake to a stop at the first floor. What is Zach's weight before the elevator starts braking?

FIGURE EX6.19 shows the velocity graph of a 75 kg passenger in an elevator. What is the passenger's weight at t=1s? At 5 s? At 9 s?

(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 m_C. Specify in terms of ℓ_A and ℓ_B , the lengths of cord from the respective masses to the pulley. (The total cord length is ℓ_A + ℓ_B.)