1.
(a) If the coefficient of kinetic friction between tires and dry pavement is 0.85, what is the shortest distance in which you can stop an automobile by locking the brakes when traveling at 26.3 m/s (about 59 mi/h)? __________ m
(b) On wet pavement the coefficient of kinetic friction may be only 0.22. How fast should you drive on wet pavement in order to be able to stop in the same distance as in part (a)? (Note: Locking the brakes is not the safest way to stop.) __________ m/s
2. The mass of Venus is 81.5% that of the earth, and its radius is 94.9% that of the earth.
(a) Compute the acceleration due to gravity on the surface of Venus from these data. (Express your answer in terms of the acceleration due to gravity on the Earth.) ________ gE
(b) If a rock weighs 53.1 N on earth, what would it weigh at the surface of Venus? _______ N
3. The acceleration due to gravity at the north pole of Neptune is approximately 10.7 m/s2. Neptune has mass 1.0 ? 1026 kg and radius 2.5 ? 104 km and rotates once around its axis in about 16 h.
(a) What is the gravitational force on a 16.0 kg object at the north pole of Neptune? ______________ N
(b) What is the apparent weight of this same object at Neptune's equator? (Note that Neptune's "surface" is gaseous, not solid, so it is impossible to stand on it.) ____________ N