How long does it take for an object to drop 100 feet?

Answer 1

by the laws of motion(s=ut+gt2) you can easily find out the answer, where s is the height, u is the initial velocity(in this case its 0), g is the acceleration due to gravity. since u is 0 the equation reduces to s=gt2 the answer is about 3.1 sec

Answer 2

The acceleration a of an object falling at the surface of the earth is 9.81 m/s^2 (or 32 feet/s^2). So its velocity v is acceleration times falling time t.
v = a * t

And its distance travelled (or height fallen) is
s(t) = -1/2 * a * t^2 + v*t + h

Where s is position, a is acceleration, t is time, v is initial velocity (when t = 0), and h is initial height (when t = 0). Using the figures given above for a, this function will consider ground to be 0, and up to be the positive direction.

One more useful equation is Vf²=Vi² + 2*a*x

Where Vf is final velocity, Vi is initial velocity, a is acceleration, and x is change in position (displacement, or the distance travelled in a straight line).

Using the last equation to answer your question:

Vf² = 0² + 2 * 32 * 100 = 6400

Vf = sqrt(6400) = 80

So, the rock would be travelling at 80 feet per second at the instant before it hits the ground. (Obviously, once it hits the ground it will be stopped). This assumes that the rock started from rest.

Note that air resistance is not taken into consideration. The equations become significantly more complex when drag is introduced, and more information about the rock than is given would be required.

Answer 3

As an object falls, its speed keeps growing, and it takes less and less time to cover each
100 feet. The first 100 feet, after the object is dropped, is covered in about 2.5 seconds.

Answer 4

300 feet, or the length of a football field.

Answer 5

Height in meters 100

Mass in kg 60

Calculate

• Speed at impact:44.27 m/s
• or159.38 km/h
• Time until impact: 4.52 s

Answer 6

4.5 seconds.