Why does the force of gravity change the speed of a satellite in an elliptical orbit?
1)The force of gravity is always tangent to the satellite motion.
2)Gravity speeds up the satellite as it moves away and slows it on its return.
3)The force of gravity is always perpendicular to the satellite motion.
4)Gravity slows the satellite as it moves away and speeds it up on its return.
only the last is true.
The correct answer is 4) Gravity slows the satellite as it moves away and speeds it up on its return.
The force of gravity acts as a centripetal force on a satellite in an elliptical orbit. According to Newton's laws of motion, the force acting on an object causes an acceleration. In the case of a satellite, the force of gravity causes the satellite to constantly change its direction, which results in an acceleration. This acceleration affects the speed of the satellite.
In an elliptical orbit, as the satellite moves away from the center of attraction (e.g., the Earth), the force of gravity decreases because the distance between the satellite and the center of attraction increases. As a result, the acceleration caused by gravity decreases, which leads to a decrease in speed. This means that the satellite slows down as it moves away.
On the other hand, as the satellite returns towards the center of attraction, the force of gravity increases because the distance between the satellite and the center of attraction decreases. Consequently, the acceleration caused by gravity increases, which leads to an increase in speed. This means that the satellite speeds up as it gets closer.
Overall, the force of gravity in an elliptical orbit acts to slow down the satellite as it moves away from the center of attraction and speeds it up as it returns towards the center.