Chapter 6
A 1.60 meter tall girl throws a football at an angle of 41.0° from the horizontal and at an initial speed of 9.40 m/s. What is the horizontal distance between the girl and the spot when the ball is again at the height above the ground from which the girl threw it?
8.90 meters
Two satellites are in orbit around a planet. One satellite has an orbital radius of 8.0 x 106 meters. The period of revolution for this satellite is 1.0 x 106 seconds. The other satellite has an orbital radius 2.0 x 107 meters. What is the satellite's period of revolution?
4.0 x 106 seconds
A car moves a distance of 420 m. Each tire on the car has a diameter of 42 cm. Which shows how many revolutions each tire makes as they move that distance?
((1.0 x 103) / π) rev
A bicyclist applies the brakes and slows the motion of the wheels. The angular momentum of each wheel then decreases from 7.0 kg*m2/s to 3.5 kg*m2/s over a period of 5.0 s. What is the angular impulse on each wheel?
-3.5 kg*m2/s
A ball resting on the floor is in what kind of equilibrium?
A. static
B. stable
C. unstable
D. disequilibrium
B. Stable
A dragonfly is sitting on a merry-go round 2.8 meters from the center. If the tangential velocity of the ride is 0.89 m/s, what is the centripetal acceleration of the dragonfly?
0.28 m/s2
Two satellites are in orbit around the same planet. Satellite A has a mass of 1.5 x 102 kg, and the satellite B has a mass of 4.5 x 103 kg. The mass of the planet is 6.6 x 1024kg. Both satellites have the same orbital radius of 6.8 x 106 m. What is the difference in the orbital periods of the satellites?
no difference
Two of the tires on a farmer's tractor have diameters of 1.5 m. If the farmer drives the tractor at a linear velocity of 3.0 m/s, what is the angular velocity of each tire?
4.0 rad/s
A 45.0 kg ice skater stands at rest on the ice. A friend tosses the skater a 5.0 kg ball. The skater and the ball then move backward across the ice with a speed of 0.50 m/s. What was the speed of the ball at the moment just before the skater caught it?
5.0 m/s
By noticing that Uranus's orbit is perturbed and by using the law of gravitation, two astronomers independently discovered
A. Neptune.
B. exceptions to the law of gravitation.
C. the law of gravitation fails at large distances.
D. Uranus has several moons.
A jogger on a riverside path sees a rowing team coming toward him. Relative to the ground, the jogger is running at 10 km/h west and the boat is sailing at 20 km/h east. How quickly does the jogger approach the boat?
30 km/h
A moon revolves around a planet with a speed of 9.0 x 103 m/s. The distance from the moon to the center of the planet is 5.43 x 106 m. What is the orbital period of the moon?
1.2π x 103 seconds
A force of 60 N is exerted on one end of a 1.0 m long lever. The other end of the lever is attached to a rotating rod that is perpendicular to the lever. By pushing down on the end of the lever, you can rotate the rod. If the force on the lever is exerted at an angle of 30° to the perpendicular to the lever, what torque is exerted on the rod?
52 N
A force of 16 N exerted against a rock with an impulse of 0.8 kg*m/s causes the rock to fly off the ground with a speed of 4.0 m/s. What is the mass of the rock?
0.2 kg
Recoil is noticeable if you throw a heavy ball while standing on roller skates To achieve a net recoil velocity of zero, then you need to
A. throw the ball a short distance.
B. throw the ball behind you.
C. throw the ball a far distance.
D. hold on to the ball.
D. Hold on to the ball.
The force exerted by a 2.0 meter massless string on a 0.82 kilogram object being swung in a horizontal circle is 4.0 Newtons. What is the tangential velocity of the object?
2.8 m/s
Imagine a satellite in orbit around a small planet. The satellite's orbital radius is 6.7 x 104 km and its speed is 2.0 x 105 m/s. What is the mass of the planet around which the satellite orbits?
(G = 6.67 x 10-11 N*m2/kg2)
4.0 x 1028 kg
A child attempts to use a wrench to remove a nut on a bicycle. Removing the nut requires a torque of 10 N*m. The maximum force the child is capable of exerting at a 90° angle is 50 N. What is the length of the wrench the child must use to remove the nut?
0.2 m
An 82 kg hockey goalie, standing at rest, catches a 0.105 kg hockey puck that is moving at a speed of 46 m/s. With what speed does the goalie slide on the ice.
0.059 m/s
Since Earth is attracted to the sun, the Earth could fall into the sun if
A. the tangential velocity would equal zero.
B. it has sufficient tangential velocity.
C. there is an equal force holding it away from the sun.
D. it has an accelerating tangential velocity
B. it has sufficient tangential velocity
A mythical warrior swings on a 5.6 kilogram mace on the end of a magically massless 86 centimeter chain in a horizontal circle above his head. The mace makes one full revolution in 1.8 seconds. Find the tension in the magical chain.
59 N
Two satellites are in orbit around a planet. Satellite S1 takes 20 days to orbit the planet at a distance of 2 x 105 km from the center of the planet. Satellite S2 takes 160 days to orbit the planet. What is the distance of satellite S2 from the center of the planet?
8 x 105 km
A thin hoop with a mass of 5.0 kg rotates about a perpendicular axis through its center. A force of 25 N is exerted tangentially to the hoop. If the hoop's radius is 2.0 m, what is its angular acceleration?
5.0 rad/s
A 40.0 kg ice skater glides with a speed of 2.0 m/s toward a 10.0 kg sled at rest on the ice. The ice skater reaches the sled and holds on to it. The ice skater and the sled then continue sliding in the same direction in which the ice skater was originally skating. What is the speed of the ice skater and the sled after they collide?
1.6 m/s
Two objects move toward each other because of a gravitational attraction which depends upon
A. the distance between their centers.
B. the objects densities.
C. the objects volumes.
D. magnetic relativity.
A. the distance between their centers