On February 20, 1962, John Glenn became the first American to orbit Earth. If John Glenn weighed 640 N on Earth's surface,

a) how much would he
have weighed if his Mercury spacecraft had (hypothetically) remained
at twice the distance from the center of Earth?

b) Why is it said that an
astronaut is never truly "weightless?"

If a rock is thrown upward on the planet mars with a velocity of 12 m/s, its height (in meters) after t seconds is given by h = 12t − 1.86t2. (a) find the velocity of the rock after two seconds. m/s (b) find the velocity of the rock when t = a. 12−3.72a m/s (c) when will the rock hit the surface? (round your answer to one decimal place.) t = s (d) with what velocity will the rock hit the surface? m/s

An astronaut floating in space is trying to use her jetpack to get back to her space station, but she is being pulled away by a nearby planet, as shown in the image below. her jetpack provides a constant thrust of 310 n. if she angles her jetpack in such a way that it cancels out the vertical force due to the planet's gravity, what is her net horizontal force? thaud 487 o a. 54.8 n toward the space station o b. 212.9 n toward the space station o c. 185.2 n toward the space station o d 956 n toward the space station

The brightest star in the night sky in the northern hemisphere is sirius. its distance from earth is estimated to be 8.7 light years. a light year is the distance light travels in one year. light travels at a speed of 3.00 × 108 m/s. calculate the distance from earth to sirius in miles. (1 mi = 5280 ft) g