Section 4 - Interactive problems: racing in circles
4.1 Use the information given in the first interactive problem in this section to calculate the initial speed that keeps the blue car on
the track and wins the race. For safety, round your answer down to the nearest 0.1 m/s. Test your answer using the
simulation.
m/s
4.2 Use the simulation in the second interactive problem in this section to calculate the initial speed that keeps the blue car on
the track and wins the race. For safety, round your answer down to the nearest 0.1 m/s.
m/sSection 5 - Newton's second law and centripetal forces
5.1 An astronaut in training rides in a seat that is moved in uniform circular motion by a radial arm 5.10 meters long. If her speed
is 15.0 m/s, what is the centripetal force on her in "G's," where one G equals her weight on the Earth?
"G's"
5.2 A ball with mass 0.48 kg moves at a constant speed. A centripetal force of 23 N acts on the ball, causing it to move in a circle
with radius 1.7 m. What is the speed of the ball?
m/s
5.3 A bee loaded with pollen flies in a circular path at a constant speed of 3.20 m/s. If the mass of the bee is 133 mg and the
radius of its path is 11.0 m, what is the magnitude of the centripetal force?
N
5.4 Fifteen clowns are late to a party. They jump into their sporty coupe and start driving. Eventually they come to a level curve,
with a radius of 27.5 meters. What is the top speed at which they can drive successfully around the curve? The coefficient of
static friction between the car's tires and the road is 0.800.
m/s
5.5 You are playing tetherball with a friend and hit
the ball so that it begins to travel in a circular
horizontal path. If the ball is 1.2 meters from
the pole, has a speed of 3.7 m/s, a mass of
0.42 kilograms, and its (weightless) rope
makes a 49° angle with the pole, find the
tension force that the rope exerts on the ball
just after you hit it.
N5.6 A car with mass 1600 kg drives around a flat circular track of radius 28.0 m. The coefficient of friction between the car tires
and the track is 0.830. How fast can the car go around the track without losing traction?
m/sSection 6 - Artificial gravity
6.1 A rotating space station has radius 1.31e+3 m, measured from the center of rotation to the outer deck where the crew lives.
What should the period of rotation be if the crew is to feel that they weigh one-half their Earth weight?sSection 7 - Interactive summary problem: race curves
7.1 Use the simulation in the interactive problem in this section to calculate the speed for (a) the first curve and (b) the second
curve that keeps the blue truck on the track and wins the race. For safety, round your answer down to the nearest 0.1 m/s.
(a) m/s
(b) m/s(^174) Copyright 2007 Kinetic Books Co. Chapter 8 Problems