Problems
Problems

 1 A body takes 10 seconds to go from rest to a speed of 50 m/s. What is the magnitude of the average acceleration of the body? 2 How would the momentum of a body change if its mass remained constant but its velocity tripled? 3 Suppose object A is four times as massive as object B. How does the acceleration of object A compare to that of object B if the same force is applied to each object? 4 What is the acceleration of a 4 kg body to which an unbalanced 18 N force is applied? 5 Identical forces are applied to two objects. The acceleration of A is 20 times the acceleration of B. How does the mass of A compare with the mass of B? 6 Suppose an astronaut in space pushes a piece of equipment away from her. The astronaut is ten times as massive as the equipment. The equipment is accelerated to a velocity of 4 m/s toward Polaris. How fast and in what direction will the astronaut move as a result of pushing the equipment? 7 How would the gravitational force between two bodies change if the mass of each were doubled and the distance between them were also doubled? 8 What is the strength of the gravitational force between the Earth and the Moon? 9 The distance between two bodies is cut in half. What would happen to the force of gravity between the two bodies? 10 What would happen to the weight of a body if it were lifted to a distance of two Earth radii above the ground? 11 What is the weight of a 50 kg person on the Earth's surface? 12 The acceleration of gravity on Mars is 0.38 Earth gravities. How much would a dog that weighs 80 N (18 pounds) on Earth weigh on Mars? 13 An asteroid is three times as far from the Sun at aphelion than at perihelion. At perihelion the orbital speed of the asteroid is 25 km/s. What is the orbital speed of the asteroid at aphelion? 14 Suppose the distance between two stars doubled while the mass of each star doubled as well. What would happen to the orbital period of the two stars? 15 A planet in a hypothetical planetary system orbits its parent star with an orbital period of 5 years and an orbital distance of 2 AU. How does the mass of the star compare to the mass of the Sun? 16 Suppose the Sun were twice as massive as it actually is. What would be the orbital period of a planet at a distance of 10 AU from the Sun? 17 The circular speed at 1 AU from the Sun is 30 km/s. What is the circular velocity at 20 AU? At 0.2 AU? 18 What is the circular speed at a distance of 5 AU from a star having a mass of 20 solar mass? 19 Neptune orbits the Sun in an almost circular orbit at a speed of 5.4 km/s. How fast would a space probe at Neptune's distance have to move to escape from the solar system? 20 What is the escape velocity from the Sun at a distance of 1000 AU?