An accelerated frame of reference is an inertial frames of reference. B. We always observe motion from an accelerated frame of reference. C. Fictitious forces occur in accelerated frames of reference. D. To an observer in an accelerated frame of reference, fictitious forces seem real. E. Centrifugal force is a real force, but centripetal force is a fictitious force.

A ball attached to an end of a 60-cm long string is revolving uniformly in a circle. How will the centripetal acceleration change if the ball's speed remains the same but the length of the string is doubled? a. The centripetal acceleration will be halved. b. The centripetal acceleration will be doubled. c. The centripetal acceleration will be quadrupled. d. The centripetal acceleration will remain the same.

You swing a weight attached to a string in a vertical circle. At the top of the circle the string just barely goes slack for an instant. At this point the centripetal acceleration of the weight isA. Greater than g.B. Less than g.C. Equal to g.D. Can’t answer without knowing the weight’s speed.

An intergalactic spaceship arrives at a distant planet that rotates on its axis with a period of T = 31 hours. The mass of the planet is M = 2.1 • 1025 kg. The spaceship enters a circular orbit with an orbital period that is equal to the planet's period for the rotation about its axis, T.   a.  Enter an expression for the radius of the spaceship’s orbit.  b.  Calculate the orbital radius in meters.

3. Two astronauts in space, each will a mass of 100 kg, are 2 meters apart from one another. a) What is the gravitational force between them? b) Both astronauts are initially at rest, but the force of gravity between them will cause them to accelerate toward one another. At what rate will they accelerate toward one another? (a = F/m.) ans. a) 1.67 x 10-7 N %3D

choose all that apply to centripetal force.   A. twice the radius needs half the centripetal force. x   B. Gravitational and electrical forces can produce centripetal forces.   C. Twice the speed needs four times the centripetal force.   D. Centripetal force depends on the mass, tangential speed and radius of the curvature.   E. Centripetal force depends on tangential spreed and radius of curvature .   F. Measured in the units of N or kg m/s^2   G. Any type of force directed towards a fixed center. I chose everything except answer E and got it wrong.

What would be the mass of a 60-kg astronaut on a planet with the same density as Earth and having twice Earth's radius? a.240 kg  b. 120 kg  c. 60 kg                                   d. 30 kg

4. A satellite 300 miles above the city in a circular orbit about the Earth is directly over a particular city at time t=0. It is traveling eastward at 16,000 mph. At the same time, a small rock very near the satellite is released from rest 300 miles above the city. How does the acceleration of the rock compare to that of the satellite in both magnitude AND direction? Explain.

A Space probe is launched from Earth headed for deep space. At a Distance of 10,000 miles from Earths center, the gravitational force on itis 600lb. What is the size of the force when it is at each if the following distances from earths center?  A.  20,000 miles b. 30,000 miles c. 100,000 miles