Question

3.	Planet Z has diameter 1.8 × 107 m. On the planet's surface, the acceleration due to gravity is 19.5 m/s2. What is the mass of the planet? Note: The constant of universal gravity (G) equals 6.674 × 10-11 N ⋅ m2/kg2.
	2.4 × 1025 kg 7.0 × 1025 kg 8.4 × 1025 kg 4.3 × 1025 kg
4.	As shown in the diagram, two massless wires connect a rotating pole to a sphere.The sphere has mass 7.2 kg and it revolves in a horizontal circle at constant speed. At this particular speed the tension is the same in both wires. What is the speed of the ball?
	2.9 m/s 4.0 m/s 5.7 m/s 4.6 m/s

5.	Two people, each of mass 85 kg, are positioned 8.0 m away from each other. What is the magnitude of the gravitational attraction between them? Note: The constant of universal gravity (G) equals 6.674 × 10-11 N ⋅ m2/kg2.
	1.1 × 103 N 7.5 × 10-9 N 8.9 × 10-11 N 6.0 × 10-8 N 7.1 × 10-10 N
6.	A racecar experiences a centripetal acceleration of 36.0 m/s2 as it travels at a constant speed of 27.0 m/s along a circular arc. What is the radius of the circle?
	0.18 m 20 m 9.3 m 14 m

7.	A particle travels in a circle of radius 76 cm and completes one revolution in 4.5 s. What is the centripetal acceleration of the particle?
	1.5 m/s2 0.97 m/s2 3.3 m/s2 2.8 m/s2

10.		Satellite B revolves around Earth 4 times a day. What is the radius of its orbit, measured from Earth's center? Assume that Earth generates the only significant gravitation attraction on the satellite. Note: The mass of Earth is 5.98 × 1024 kg, and the constant of universal gravity (G) equals 6.674 × 10-11 N ⋅ m2/kg2.
		1.68 × 107 m 6.03 × 106 m 2.11 × 107 m 6.70 × 107 m

11.	An astronaut has weight W on Earth. The astronaut travels to a planet that has a mass 4 times greater than Earth's mass, and its radius is 2 times greater than Earth's radius. What is the astronaut's weight on the planet?
	4W 0.5W W 2W
12.	The gravitational acceleration at the surface of planet X is 11.6 m/s2, and the radius of the planet is 66,500 km. An astronaut is hovering at height h above the planet's surface, and she notices her weight is the same as it is on Earth. What is h?
	8200 km 7000 km 5800 km 9400 km

13.	Earth's radius is 6380 km. An object is dropped from a height 622 km above Earth's surface. What is its initial acceleration in terms of g, the acceleration constant due to gravity at Earth's surface?
	0.375g 0.831g 1.33g 0.426g
14.	At the top of a looped section of roller coaster track, the car and rider are completely upside down. What information is necessary to calculate the minimum speed of the car that will prevent a rider from falling out of it? Assume the rider is not strapped into the car.
	the radius of the loop, the mass of the rider. and the mass of the car the radius of the loop the mass of the rider and the width of the track the radius of the loop and the mass of the rider

Answer 1