Answer:
A (2066,6 N)
Explanation:
Use the Work formula
62.000J = F . 30
62.000/30 = 2066,6 N
The amout of time it took to move the rock doesn´t matter at all.
It is called a distraction variable, We don´t need it to solve the problem it is there just to confuse.
Answer:
The speed decreases.
Explanation:
This can be explained using the conservation of linear momentum.
Since there is no friction, the initial moment of the train must be equal to its linear moment after it is filled with water.
the initial linear momentum is
where 
is the initial mass of the train, and 
the initial speed of the train.
And linear momentum after the water filled the train car is
where 
is mass of the train after the rain, and 
the speed of the train after the rain
<u>the equality must be fulfilled:</u>
We know that if water is added to the train, that is the mass after the water is added, is greater than which is the mass of the train without the water.
Therefore, in order for the conservation of the linear momentum to be fulfilled:
the speed after the water is added ( ) must be smaller than the initial train speed ( ) . So the speed of the car decreases.
Answer:
Associations Clusters
Explanation:
There is three basic type of clusters, globular clusters, open clusters, associations clusters. Associations cluster consist of younger stars that is younger than globular and open clusters stars.
Answer:
b) True. the force of air drag on him is equal to his weight.
Explanation:
Let us propose the solution of the problem in order to analyze the given statements.
The problem must be solved with Newton's second law.
When he jumps off the plane
fr - w = ma
Where the friction force has some form of type.
fr = G v + H v²
Let's replace
(G v + H v²) - mg = m dv / dt
We can see that the friction force increases as the speed increases
At the equilibrium point
fr - w = 0
fr = mg
(G v + H v2) = mg
For low speeds the quadratic depended is not important, so we can reduce the equation to
G v = mg
v = mg / G
This is the terminal speed.
Now let's analyze the claims
a) False is g between the friction force constant
b) True.
c) False. It is equal to the weight
d) False. In the terminal speed the acceleration is zero
e) False. The friction force is equal to the weight
G = 9.81 m/sec^2) g = 9.81
<span>Solving for velocity : </span>
<span> = 2gh </span>
<span>v = </span>
<span>v = (2 x 9.81 x 10)^1/2 </span>
<span>v = 196.2 m/sec (answer)</span>
