What is the speed of the ball just before it strikes the ground?

In summary, a ball is thrown from the top of a building with an initial speed of 23 m/s at an angle of 47 degrees to the horizontal. It is thrown at a height of 46 m above the ground and hits the ground 82.0127 m from the base of the building. The acceleration of gravity is 9.8 m/s^2. The question asks for the speed of the ball just before it strikes the ground, which can be calculated by finding the maximum height (14.4363 m) and the time at maximum height (1.71644 s), then using the equation vf = vi - gt. However, the answer of v = -16.8211 m/s is incorrect and
  • #1
gap0063
65
0
A ball is thrown from the top of a building
upward at an angle of 47 ◦ to the horizontal
and with an initial speed of 23 m/s, as in
the figure. The ball is thrown at a height of
46 m above the ground and hits the ground
82.0127 m from the base of the building.
The acceleration of gravity is 9.8 m/s2 .

What is the speed of the ball just before it
strikes the ground?
Answer in units of m/s.


I have tried calculating the max height (14.4363m) and the time @ max height (1.71644s) then doing vf-=vi-gt => vf=-9.8(1.71644)=-16.8211 m/s (wrong)

not sure what else to try...
 
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  • #2
I'm not sure how you managed to get max height at 14.4363m when the ball is ''thrown at a height of 46 m above the ground.'' Try redrawing your diagram, I can show you how to get answer, just tell me if the answer is v=56.16m/s otherwise I will have to recheck my drawing.

Best of luck
 
  • #3
the answer is not v= 56.16 m/s

thanks though
 

FAQ: What is the speed of the ball just before it strikes the ground?

What factors affect the speed of a ball just before it strikes the ground?

The speed of a ball just before it strikes the ground can be affected by several factors, including the initial velocity of the ball, the angle at which it is thrown, air resistance, and the force of gravity acting on the ball. Other factors such as the surface on which the ball is bouncing and external forces can also influence its speed.

How is the speed of a ball just before it strikes the ground calculated?

The speed of a ball just before it strikes the ground can be calculated using the formula v = √(u² + 2as), where v is the final velocity, u is the initial velocity, a is the acceleration due to gravity, and s is the distance traveled. This formula takes into account the initial velocity, acceleration, and distance traveled by the ball.

Does the mass of the ball affect its speed just before it strikes the ground?

According to the formula for calculating the speed of a ball, the mass of the ball does not affect its speed just before it strikes the ground. This is because the mass of the ball is not included in the formula, and only factors such as initial velocity, acceleration, and distance traveled are taken into account.

Can the speed of a ball just before it strikes the ground be greater than its initial velocity?

Yes, the speed of a ball just before it strikes the ground can be greater than its initial velocity. This can happen if the ball is thrown at an upward angle or if there is a force acting on the ball that increases its speed, such as wind or a bounce off another surface.

How does air resistance affect the speed of a ball just before it strikes the ground?

Air resistance can have a significant impact on the speed of a ball just before it strikes the ground. As the ball travels through the air, it experiences resistance from the air molecules, which can slow down its speed. This can be particularly noticeable for objects with a large surface area, such as a beach ball, compared to smaller objects like a golf ball.

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