Finding the Speed of a Falling Ball with Constant Acceleration

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SUMMARY

The discussion centers on calculating the speed of a small steel ball dropped from rest, which takes 0.5 seconds to fall 1.25 meters under constant acceleration. The correct approach involves using the equations of motion for constant acceleration: \(s = \frac{1}{2}at^2 + v_0t + x_0\) and \(v = at + v_0\). The initial calculation of \(5 \, \text{m/s}\) is derived from the average speed formula \(s = t \cdot \frac{(u + v)}{2}\), where \(u\) is the initial speed (0) and \(v\) is the final speed. Thus, the final speed of the ball after falling 1.25 meters is confirmed to be \(5 \, \text{m/s}\).

PREREQUISITES
  • Understanding of kinematic equations for constant acceleration
  • Familiarity with basic physics concepts such as speed, distance, and time
  • Knowledge of the formula \(s = vt\) for constant speed
  • Ability to manipulate algebraic equations
NEXT STEPS
  • Study the derivation of the equations of motion for constant acceleration
  • Learn about free fall and gravitational acceleration
  • Explore the concept of average speed in physics
  • Practice solving problems involving kinematic equations
USEFUL FOR

Students studying physics, educators teaching kinematics, and anyone interested in understanding motion under constant acceleration.

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Homework Statement



A small steel ball, dropped from rest, takes 0.5s to fall through a vertical distance of 1.25m.
Determine the actual speed of the ball when it has fallen through a vertical distance of 1.25m, assuming that acceleration is constant.


Homework Equations



v=s/t

The Attempt at a Solution



Long ago I was helped by a friend to get the result
( 1.25m x 2 ) / 0.5s = 5ms-1

but I've forgotten how did he come to that conclusion, and the reason behind (1.25mx2), help is much appreciated .
 
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The formula [itex]s=vt[/itex] is only valid for constant speed. Does an object fall with constant speed?

Your friend used the following, correct equations:

1) [itex]s=\frac{1}{2}at^2+v_0t+x_0[/itex]
2) [itex]v=at+v_0[/itex]

These are valid for constant acceleration. You will need to combine both of them to get the answer.
 
s = t*(u+v)/2
 

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