Suppose that you are swimming in a river while a friend watches from the shore. In calm water, you swim at a speed of 1.25 m/s . The river has a current that runs at a speed of 1.00 m/s. If you are swimming upstream (i.e., against the current), at what speed does your friend on the shore see you moving?
1.25m/s-1m/s=.25m/s
Well, in this situation, your friend on the shore might see you moving at a speed of negative 0.25 m/s. Why negative? Well, it's because you're swimming against the current and it's trying to push you back. It's like going against the flow of traffic while riding a unicycle on a slippery banana peel. So, your friend might think you're making some questionable life choices, but hey, at least it makes for an entertaining sight!
To determine the speed at which your friend on the shore sees you moving when you're swimming upstream against the current, you need to consider the relative velocity.
The relative velocity is the difference between your swimming speed and the speed of the river current. So, to calculate your speed as seen by your friend on the shore, you subtract the speed of the river current from your swimming speed.
Let's perform the calculation:
Relative velocity = Swimming speed - River current speed
Relative velocity = 1.25 m/s - 1.00 m/s
Relative velocity = 0.25 m/s
Therefore, when you are swimming upstream against the current, your friend on the shore sees you moving at a speed of 0.25 m/s.
To find the speed at which your friend on the shore sees you moving while you swim upstream against the current, you need to consider the relative velocities.
When swimming against the current, your speed relative to the water will be your swimming speed minus the speed of the current. In this case, your swimming speed is 1.25 m/s, and the current's speed is 1.00 m/s. So, your speed relative to the water will be:
Relative speed against the current = Swimming speed - Current speed
= 1.25 m/s - 1.00 m/s
= 0.25 m/s.
Since you are swimming against the current, your friend on the shore will see you moving with the speed equal to the speed of the current minus your relative speed. Therefore, the speed at which your friend sees you moving will be:
Friend's speed = Current speed - Relative speed against the current
= 1.00 m/s - 0.25 m/s
= 0.75 m/s.
Thus, your friend on the shore will see you moving at a speed of 0.75 m/s while you swim upstream against the current.