Find final velocity in a horizontal projectile motion

In summary, a ball is thrown from a cliff and reaches the ground after 2.5 seconds. Using the equations Δy = 2⋅g⋅t^2 and Vfy = g⋅t, we can determine that the height of the cliff is 30.6m and the vertical velocity at impact is 24.5m/s. However, without knowing the initial horizontal velocity or angle of the throw, it is not possible to calculate the horizontal distance the ball reached.
  • #1
vAhmed
5
0

Homework Statement


A ball was thrown from a cliff, it reached to the ground after 2.5 seconds.
a) Find the height of the cliff.
b) Find the horizontal distance the ball reached.

Homework Equations


Δy = 2⋅g⋅t^2
Vfy = g⋅t
√(Vfy)^2+(Vfx)^2
Δx= Vx⋅t

The Attempt at a Solution


I've found Δy=30.6m and Vfy=24.5m/s but I couldn't find Vfx without Δx using the equation Δx=Vx⋅t
How can I find Vfx in order to calculate Vf
 
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  • #2
You need to know the initial velocity and the angle which thrown. If it was thrown at a 0° angle to the horizontal, then the initial velocity will not contribute to how long it takes to hit the ground.

If you are assuming negligible air resistance, then you can assume the final horizontal velocity will be approximately equal to the initial horizontal velocity.

If the problem doesn't give an initial velocity, You could take something known like the fastest baseball thrown, and use that to find an upper bound.o0)
 
  • #3
+1

vAhmed said:
I've found Δy=30.6m and Vfy=24.5m/s

Those answers look ok but as Scott said you don't have enough info in the problem statement to answer b). Did you miss out something?
 

What is horizontal projectile motion?

Horizontal projectile motion is a type of motion in which an object is launched or thrown horizontally, meaning it moves parallel to the ground.

How is final velocity calculated in horizontal projectile motion?

The final velocity in horizontal projectile motion is calculated by using the formula: Vf = Vi + at, where Vf is the final velocity, Vi is the initial velocity, a is the acceleration, and t is the time.

What is the role of gravity in horizontal projectile motion?

In horizontal projectile motion, gravity plays a role in the vertical direction as it causes the object to accelerate downward. However, it does not affect the horizontal motion of the object.

Can the final velocity in horizontal projectile motion be negative?

Yes, the final velocity in horizontal projectile motion can be negative if the object is launched in the opposite direction of its initial velocity. This indicates that the object is slowing down.

How does air resistance affect the final velocity in horizontal projectile motion?

Air resistance can affect the final velocity in horizontal projectile motion by causing the object to slow down as it travels through the air. This means that the final velocity may be lower than the calculated value due to the resistance of the air.

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