If you decrease the length of a wire, what effect will it have on resistance

Use the work—energy theorem to solve each of these problems. You can use Newton's laws to check your answers. Neglect air resist

andreyandreev [35.5K]

Answer:

a) It is moving at $43.15\frac{m}{s^{2}}$ when reaches the ground.

b) It is moving at $101.44\frac{m}{s^{2}}$ when reaches the ground.

Explanation:

Work energy theorem states that the total work on a body is equal its change in kinetic energy, this is:

$W=K_f-K_i$ (1)

with W the total work, Ki the initial kinetic energy and Kf the final kinetic energy. Kinetic energy is defined as:

$K=\frac{mv^2}{2}$ (2)

with m the mass and v the velocity.

Using (2) on (1):

$W=\frac{mv_f^2}{2}-\frac{mv_i^2}{2}$ (3)

In both cases the total work while the objects are in the air is the work gravity field does on them. Work is force times the displacement, so in our case is weight (w=mg) of the object times displacement (d):

$W=Fd=wd=mgd$ (4)

Using (4) on (3):

$mgd=\frac{mv_f^2}{2}-\frac{mv_i^2}{2}$ (5)

That's the equation we're going to use on a) and b).

a) Because the branch started form rest initial velocity (vi) is equal zero, using this and solving (5) for final velocity:

$v_f=\sqrt{\frac{2mgd}{m}}=\sqrt{2gd}=\sqrt{2*9.8*95}$

$v_f=43.15\frac{m}{s^{2}}$

b) In this case the final velocity of the boulder is instantly zero when it reaches its maximum height, another important thing to note is that in this case work is negative because weight is opposing boulder movement, so we should use -mgd:

$-mgd=-\frac{mv_i^2}{2}$

Solving for initial velocity (when the boulder left the volcano):

$v_i=\sqrt{\frac{2mgd}{m}}=\sqrt{2gd}=\sqrt{2*9.8*525}$

$v_i=101.44 \frac{m}{s^{2}}$

3 0

3 years ago

Pablo is asked to think about his favorite birthday party, and he pictures a cake with candles and frosting and he can even reme

Veseljchak [2.6K]

The correct answer is B. Analogical

4 0

4 years ago

The ease with which a memory can be retrieved is influenced by all of the following EXCEPT

34kurt

Hi! I just took this lesson, the answer is: "The person's belief in the information"

I hope this helps!

4 0

3 years ago

Read 2 more answers

Density problems brainless anwser to first person who does it

Aleks04 [339]

<u>First question:</u>

Density = $\frac{mass}{volume}$

Mass = density × volume

The density of the cube is 1.2g/cm³

The volume of the cube is given by side × side × side:

Volume = 7cm × 7cm × 7cm = 347cm³

Mass = 1.2g/cm³ × 343cm³ = 411.6g

*Hint: Just apply the formula Density = $\frac{mass}{volume}$ to solve the next questions.

4 0

3 years ago

Patricia stands on a hill at an angle of 30 degrees. there is enough friction to stop her from sliding down the hill. Which free

makvit [3.9K]

Correct free-body diagram is option A)

Explanation:

There are three forces acting on Patricia:

Her weight, which is the force of gravitational attraction exerted by the Earth on her, whose magnitude is $mg$ (where m= mass and g= acceleration of gravity). The direction of this force is vertically downward.
The normal force, exerted by the plane on Patricia, which acts always up perpendicular to the plane
The force of friction, which prevents Patricia from sliding. The force of static friction acts in the direction opposite to the direction of motion if the body is let moving: so here, the force of friction acts up along the plane (parallel to the plane)

Therefore, the correct choice here is option A), because:

The weight acts vertically downward
The normal force acts perpendicular to the plane
The force of friction acts parallel to the plane

Learn more about forces:

brainly.com/question/8459017

brainly.com/question/11292757

brainly.com/question/12978926

#LearnwithBrainly

4 0

4 years ago