Could you scroll up a little so I can see the first part of the question- I MIGHT be able to help you then. Thanks!
Answer:
Approximately
upwards (assuming that
.)
Explanation:
External forces on this astronaut:
- Weight (gravitational attraction) from the earth (downwards,) and
- Normal force from the floor (upwards.)
Let
denote the magnitude of the normal force on this astronaut from the floor. Since the direction of the normal force is opposite to the direction of the gravitational attraction, the magnitude of the net force on this astronaut would be:
.
Let
denote the mass of this astronaut. The magnitude of the gravitational attraction on this astronaut would be
.
Let
denote the acceleration of this astronaut. The magnitude of the net force on this astronaut would be
.
Rearrange
to obtain an expression for the magnitude of the normal force on this astronaut:
.
Answer:
Probability of tunneling is 
Solution:
As per the question:
Velocity of the tennis ball, v = 120 mph = 54 m/s
Mass of the tennis ball, m = 100 g = 0.1 kg
Thickness of the tennis ball, t = 2.0 mm = 
Max velocity of the tennis ball,
= 89 m/s
Now,
The maximum kinetic energy of the tennis ball is given by:

Kinetic energy of the tennis ball, KE' = 
Now, the distance the ball can penetrate to is given by:


Thus



Now,
We can calculate the tunneling probability as:



Taking log on both the sides:


Answer:
The planet will move from east to west for a couple of months in the night sky.
Explanation:
Retrograde motion is an optical effect due to the fact that Earth rotates more quickly than the planet that apparently has a retrograde motion in the sky.
For example, Saturn has a slower speed in its orbit around the Sun. That means that the Earth will pass it, and that will give the effect that the planet is moving backward. That same scenario can be seen between two cars on a highway, the faster car will see the slower car when it passes as it is moving for a short fragment of time in backward.
Remember that the planets in the night sky move from west to east, in the case of a planet with retrograde motion, it will move from east to west for a couple of months.