A bullet is fired horizontally from the top of a cliff with a speed of 30m/s.assuming that there is no air resistance, what will be its speed 3sec later?

Since there is no air resistance, the horizontal speed of the bullet remains constant.

Given that the bullet was fired horizontally with a speed of 30 m/s, its horizontal speed will remain 30 m/s after 3 seconds.

Therefore, the speed of the bullet 3 seconds later will be 30 m/s.

To determine the speed of the bullet 3 seconds later, we need to consider that the bullet is fired horizontally from the top of a cliff with a speed of 30 m/s. Assuming there is no air resistance, the horizontal speed will remain constant throughout its motion.

Since there is no vertical component to the bullet's initial velocity, it will only be affected by gravity in the vertical direction. The acceleration due to gravity is approximately 9.8 m/s², and it acts downward.

First, let's determine how far the bullet would have traveled horizontally after 3 seconds by using the formula:

distance = initial velocity × time

Given that the initial horizontal velocity is 30 m/s and the time is 3 seconds, we can calculate the horizontal distance:

distance = 30 m/s × 3 s = 90 meters

Therefore, after 3 seconds, the bullet would have traveled 90 meters horizontally.

Now, since there is no air resistance, the bullet's vertical velocity will be affected by gravity. After 3 seconds, the bullet would have fallen vertically due to the acceleration of gravity. We can calculate this using the formula:

final velocity = initial velocity + acceleration × time

The initial vertical velocity is 0 m/s (as there is no vertical component to the bullet's initial velocity), and the acceleration due to gravity is approximately 9.8 m/s². Plugging these values into the formula:

final velocity = 0 m/s + 9.8 m/s² × 3 s = 29.4 m/s

Therefore, 3 seconds later, the bullet's vertical speed would be 29.4 m/s (directed downward due to gravity). However, since there is no vertical component to the bullet's initial velocity, the vertical speed does not affect the horizontal speed, and thus, the bullet's horizontal speed would still be 30 m/s after 3 seconds.

horizontal speed u = 30 forever

so what is vertical speed v?
v = g t
v = 9.81(3)

that is also around 30 m/s
so
speed = sqrt(u2+v^2)
= sqrt 1800)
= about 42
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