# Force and Acceleration

problem 2 A weight-conscious penguin with a mass of 15.0 kg rests on a bathroom scale (see figure below). What are (a) the penguin's weight W and (b) the normal force N on the penguin? (c) What is the reading on the scale, assuming it is calibrated in weight units?

problem 3 If a nucleus captures a stray neutron, it must bring the neutron to a stop within the diameter of the nucleus by means of the strong force. That force, which "glues" the nucleus together, is essentially zero outside the nucleus. Suppose that a stray neutron with an initial speed of 1.4 X 107 m/s is just barely captured by a nucleus with diameter d = 1.0 X 10-14 m. Assuming that the force on the neutron is constant, find the magnitude of that force. The neutron's mass is 1.67 X 10-27 kg.

problem 4 Sunjamming. A "sun yacht" is a spacecraft with a large sail that is pushed by sunlight. Although such a push is tiny in everyday circumstances, it can be large enough to send the spacecraft outward from the Sun on a cost-free but slow trip. Suppose that the spacecraft has a mass of 900 kg and receives a push of 20 N.(a) What is the magnitude of the resulting acceleration? If the craft starts from rest, (b) how far will it travel in 1 day and (c) how fast will it then be moving?

problem 5 A 40 kg girl and an 8.4 kg sled are on the surface of a frozen lake, 15 m apart. By means of a rope, the girl exerts a horizontal 5.2 N force on the sled, pulling it toward her. (a) What is the acceleration of the sled? (b) What is the acceleration of the girl? (c) How far from the girl's initial position do they meet,...

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