The magnitude of the work done to push the object is 90,000 J
<h3>
When is Work done on a body ?</h3>
Work is done on a body when the direction of the force applied is parallel to the direction of the displacement of the body.
The following parameters are given;
First convert the distance in kilometer to meter by multiplying it by 1000
S = 1.2 x 1000 = 1200 m
From the definition of work,
W = F x S
Substitute the parameters into the formula
W = 75 x 1200
W = 90,000 J
Therefore, the magnitude of the work done to push the object is 90,000 J
Learn more about Work here: brainly.com/question/25573309
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I believe that formula is incomplete, if it is derived from the kinematic equations.
The full formula being
where:
s is the displacement (or how far she travelled in your question)
u is the initial velocity, which I think can be assumed to be 0 m/s
t is the time taken which is 120 s
a is the acceleration due to gravity which points down in a negative y direction, which is -9.8 m/
Since initial velocity, u, is assumed to be 0 m/s the equation becomes:
Substitute in a = -9.8m/ and t = 120 s and calculate your answer.
Tell me what you calculate the answer to be (don't forget units) and I'll let you know if it's right.
Answer: option D. the ratio of the population of male deer is not constant.
Explanation:
The bar graph permits to compare the results for two different populations: male and female deer in a very easy visual way.
These features are remarkable:
- The polulation of male deer (blue bars) decrease from 1961 to 1971, then increase in the next 10 year, decrease in the next decade, and increase for the next two decades. So, its trend is erratic, with ups and downs.
This discards the option A, which states that the population of male deer increases each decade from 1961 to 2011.
- The population of female deer (purple or brown bars) decreases every decade.
This discards the option B. which states that when the polulation of male deer increases, the poluplation of female deer also increases.
- The populations never are equal, hence this discards the option C.
- Since, one popultion increases and decreases, while the other population only decreases, you conclude that the ratio of the population of male deer to female deer is not constant, which is the option D.
<h2>
The speed of the rock just before it reaches the water 25.0 m below the point where the rock left your hand is 45.06 m/s</h2>
Explanation:
First let us find the initial velocity,
We have after 8 seconds the displacement is zero,
We have equation of motion s = ut + 0.5 at²
Initial velocity, u = ?
Acceleration, a = -9.81 m/s²
Time, t = 8 s
Displacement,s = 0 m
Substituting
s = ut + 0.5 at²
0 = u x 8 + 0.5 x -9.81 x 8²
u = 39.24 m/s
Initial velocity is 39.24 m/s.
Now this case is similar to case where a rock is thrown at 39.24 m/s downward.
We have equation of motion v² = u² + 2as
Initial velocity, u = 39.24 m/s
Acceleration, a = 9.81 m/s²
Final velocity, v = ?
Displacement, s = 25 m
Substituting
v² = u² + 2as
v² = 39.24² + 2 x 9.81 x 25
v = 45.06 m/s
The speed of the rock just before it reaches the water 25.0 m below the point where the rock left your hand is 45.06 m/s