A rock dropped from a small bridge encounters no air resistance and hits the pond below 1.0 s later.
If it had been thrown horizontally with a speed of 10m/s , then it would have hit the water
A. more than 1.0s later, since it has a greater distance to travel.
B. 1.0s later, since the vertical motion is not affected by the horizontal motion.
C. less than 1.0 s later, since the higher speed would tend to get the ball to the ground more quickly.
Hint: The horizontal component of the velocity does not affect the vertical motion. Whether you simply release the rock at t=0 or throw it horizontally, the initial vertical velocity component is zero.
With that in mind, you should be able to figure out the answer.
To solve this problem, we need to understand the concept of projectile motion. When the rock is dropped vertically from the bridge, it only undergoes vertical motion, and the time it takes to hit the water is solely determined by the vertical distance and the acceleration due to gravity.
In the case of the rock thrown horizontally with a speed of 10 m/s, the horizontal component of its velocity does not affect its vertical motion. Regardless of the horizontal velocity, the vertical motion is influenced solely by gravity.
Since the vertical motion is not affected by the horizontal motion, the time it takes for the rock to hit the water remains the same, which is 1.0 s.
Therefore, the correct answer is B. 1.0s later, since the vertical motion is not affected by the horizontal motion.