Answer:
Planets that are farther from the sun than the earth (all but Mercury and Venus) will exhibit retrograde motion.
If the position of the planet is observed relative to the background stars, the planet will appear to move backward relative to the stars when the earth is moving in an Eastward direction faster than the planet, and the planet appears to move backwards relative to the stars
(The planet will be on the side of the earth that is opposite that of the sun)
The parallel component is given by
F=180cos(25)=163.14N
Answer: The force needed is 140.22 Newtons.
Explanation:
The key assumption in this problem is that the acceleration is constant along the path of the barrel bringing the pellet from velocity 0 to 155 m/s. This means the velocity is linearly increasing in time.
The force exerted on the pellet is
F = m a
In order to calculate the acceleration, given the displacement d,

we will need to determine the time t it took for the pellet to make the distance through the barrel of 0.6m. That time can be determined using the average velocity of the pellet while traveling through the barrel. Since the velocity is a linear function of time, as mentioned above, the average is easy to calculate as:

This value can be used to determine the time for the pellet through the barrel:

Finally, we can use the above to calculate the force:
