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D Question 1 2 pts If the distance between the Earth and the Moon suddenly decreased by a factor of 1/2 (i.e. halves), how would the force of gravity between them change? I would decrease by 1/2 I would increase by 4x It would decrease by 1/ O It would double

Question 2 2 pts Ignoring air resistance, if a 20 kg ball and a 2 kg crate were both dropped from the top of a building, the acceleration of the crate would be the acceleration of the ball. 2x 1/2 x O equal to O 10x O 1/10 x

The majority of satellites orbiting the Earth do so at altitudes between 160 and 2,000 kilometers. Find the tangential velocity needed to keep a satellite in orbit at an altitude of 1000 km from the surface of the Earth. Answer this problem in the following two questions below.

Question 3 2 pts mu First, you want to find an equation for the velocity at which the centripetal force F is equal to the force of gravity F, = GMm Set Fc = F, and solve for v, what do you get? Ov GmM U Or Gm GM U o Gm

Question 4 2 pts Now that you have an equation for v, plug the following values in the right variables in the equation and calculate the velocity. Gravitational Constant = 6.7 x 10-11 mkg 1 s 2 Mass of the Earth = 6 x 10^24 kg Radius of the Earth = 6,370 km Give your answer in units of km/s HINT: Add the Radius of the Earth and the altitude of the satellite to get rier-Radius of the Earth + 1000 km (and don't forget to change the units to meters),

If you where to shrink the Earth and put all of its mass into a small enough radius, you could form a black hole with mass equal to the mass of the Earth. Calculate the radius at which the Earth would become a black hole. Answer this problem in the following two questions below.

D Question 5 2 pts First you need find an equation for the escape velocity and then solve for the radius r. The escape velocity is that at which the Kinetic Energy KE = mu’is equal to the Potential Energy PE = mgr (notice that you are used to see PE = mgh, since we usually measure potential energy relative to the surface of the earth, now we want to find the potential at the surface of the earth, so h=r). Notice though that the gravitational acceleration g is not constant if you change the radius , we can find how g depends on r using Newton's Law of Gravitation and Newton's 2nd Law: GmM 9 GM m ma Set KE = PE and solve for r, what do you get? HINT: Remember to setg GM 2 O r = 2GM v Or= 2GM Or=2 913 32 OF GM

Question 6 2 pts Now that you have an equation for r, set the escape velocity to the speed of light, i.e. v=C (that is how we define a black hole), and the mass M to the mass of the Earth. Use the values below in the equation and calculater. C = 3 x 108 m/s Gravitational Constant = 6.7 x 10-11 mkg 1 s 2 Mass of the Earth = 6 x 10^24 kg Give your answer in units of mm (millimeters) I

Question 7 1 pts while non- Inertial reference frames are those that are [Select] [Select] inertial reference frames are [Select] undergoing acceleration not undergoing acceleration Question 8 2 pts What were the two postulates that Einstein based Special Relativity on The speed of light must be the same for all observers independent on their relative motions. The laws of physics are the same and can be stated in their simplest form in all inertial frames of reference. Time and distance measurements must the same for all observers independent on their relative motions

Question 9 1 pts Special Relativity applies only to [Select] while General Relativity extends Special Relativity to explain phenomena in [Select] [Select non-inertial frames Inertial frames