Chapter 4

  1. (p.103 prob.60) A person has a reasonable chance of surviving an automobile crash if the deceleration is no more than 30"g's." Calculate the force on a 70-kg person accelerating at this rate. What distance is traveled if h brought to rest at this rate from 90km/h?

    2. Answer.

     

  2. (p.104 prob.67) (a) In Fig. 4-54, if m1 = m2 = 1.00kg and q = 30°, what will be the acceleration of the system? (b) If m1= 1.00kg and q = 30°, and the system remains at rest, what must the mass m2 be? (c) Calculate the tension in the cord for (a) and (b).

    Answer.

     

  3. (p.104 prob.72) A bicyclist can coast down a 5.0° hill at a constant speed of 6.0km/h. If the force of air resistance is proportional to the speed v so that Fair = cv, calculate (a) the value of the constant c, and (b) the average force that must be applies in order to descend the hill at 20.0km/h. This mass of the cyclist plus bicycle is 80.0kg.

    Answer.

     

  4. (.105 prob.76) A jet aircraft is climbing at an angle 45° above the horizontal and is also accelerating at 4.5m/s2. What is the total force that this cockpit seat exerts on the 75-kg pilot?

    Answer.

     

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