If an object is dropped from an initial height [tex]\( h \)[/tex], its velocity at impact with the ground is given by

[tex]\[ v = \sqrt{2 g h} \][/tex]

where [tex]\( g \)[/tex] is the acceleration due to gravity and [tex]\( h \)[/tex] is the initial height.

(a) Find the initial height (in feet) of an object if its velocity at impact is [tex]\( 38 \, \text{ft/sec} \)[/tex]. (Assume that the acceleration due to gravity is [tex]\( g = 32 \, \text{ft/sec}^2 \)[/tex].) Round to the nearest hundredth of a foot, if necessary.

(b) Find the initial height (in meters) of an object if its velocity at impact is [tex]\( 16 \, \text{m/sec} \)[/tex]. (Assume that the acceleration due to gravity is [tex]\( g = 9.8 \, \text{m/sec}^2 \)[/tex].) Round to the nearest tenth of a meter.



Answer :

To solve the given problem, we need to use the provided formula for the velocity of an object at impact with the ground:

[tex]\[ v = \sqrt{2gh} \][/tex]

Where:
- [tex]\( v \)[/tex] is the velocity at impact,
- [tex]\( g \)[/tex] is the acceleration due to gravity,
- [tex]\( h \)[/tex] is the initial height.

We need to rearrange the formula to solve for the initial height [tex]\( h \)[/tex]:

[tex]\[ v^2 = 2gh \][/tex]
[tex]\[ h = \frac{v^2}{2g} \][/tex]

### Part (a)

Given:
- Velocity at impact [tex]\( v = 38 \)[/tex] ft/sec,
- Acceleration due to gravity [tex]\( g = 32 \)[/tex] ft/sec².

We need to find the initial height [tex]\( h \)[/tex]:

[tex]\[ h = \frac{v^2}{2g} \][/tex]

Substitute the given values:

[tex]\[ h = \frac{38^2}{2 \times 32} \][/tex]

First, calculate [tex]\( 38^2 \)[/tex]:

[tex]\[ 38^2 = 1444 \][/tex]

Then, calculate the denominator [tex]\( 2 \times 32 \)[/tex]:

[tex]\[ 2 \times 32 = 64 \][/tex]

Now, divide the results:

[tex]\[ h = \frac{1444}{64} \][/tex]

This simplifies to:

[tex]\[ h \approx 22.56 \text{ feet (rounded to the nearest hundredth)} \][/tex]

### Part (b)

Given:
- Velocity at impact [tex]\( v = 16 \)[/tex] m/sec,
- Acceleration due to gravity [tex]\( g = 9.8 \)[/tex] m/sec².

We need to find the initial height [tex]\( h \)[/tex]:

[tex]\[ h = \frac{v^2}{2g} \][/tex]

Substitute the given values:

[tex]\[ h = \frac{16^2}{2 \times 9.8} \][/tex]

First, calculate [tex]\( 16^2 \)[/tex]:

[tex]\[ 16^2 = 256 \][/tex]

Then, calculate the denominator [tex]\( 2 \times 9.8 \)[/tex]:

[tex]\[ 2 \times 9.8 = 19.6 \][/tex]

Now, divide the results:

[tex]\[ h = \frac{256}{19.6} \][/tex]

This simplifies to:

[tex]\[ h \approx 13.1 \text{ meters (rounded to the nearest tenth)} \][/tex]

Therefore, the solutions are:
- Part (a): The initial height is [tex]\( 22.56 \)[/tex] feet.
- Part (b): The initial height is [tex]\( 13.1 \)[/tex] meters.