Answer:
1703.24J
Explanation:
Given parameters:
Mass of brick = 7.9kg
Height of building = 22m
Unknown:
Potential energy of the brick = ?
Solution:
The potential energy of a body is the energy at rest of the body. Mathematically;
P.E = mgh
m is the mass of the brick
g is the acceleration due to gravity
h is the height of the building
Insert the given parameters and solve;
P.E = 7.9 x 9.8 x 22 = 1703.24J
Answer:
<em>The final speed of the second package is twice as much as the final speed of the first package.</em>
Explanation:
<u>Free Fall Motion</u>
If an object is dropped in the air, it starts a vertical movement with an acceleration equal to g=9.8 m/s^2. The speed of the object after a time t is:
And the distance traveled downwards is:
If we know the height at which the object was dropped, we can calculate the time it takes to reach the ground by solving the last equation for t:
Replacing into the first equation:
Rationalizing:
Let's call v1 the final speed of the package dropped from a height H. Thus:
Let v2 be the final speed of the package dropped from a height 4H. Thus:
Taking out the square root of 4:
Dividing v2/v1 we can compare the final speeds:
Simplifying:
The final speed of the second package is twice as much as the final speed of the first package.
The initial velocity of Ms. Stafford is
, while her acceleration is
This is a uniform accelerated motion, so we can calculate the total distance travelled by Ms. Stafford in a time of
using the law of motion for a uniform accelerated motion: