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3 years ago

A rock is thrown straight up with an initial velocity of 15.0 m/s. Ignore energy lost to air friction. How high will the rock ri

se?

Physics

1 answer:

Furkat [3]3 years ago

5 0

$h=v_0t- \frac{1}{2} gt^2\\h=15t-\frac{1}{2}(9.8) t^{2}\\ \\ 
v_f=v_0-gt\;\;\;\Rightarrow t= \frac{v_f-v_0}{-g} = \frac{0-15}{-9.8} \approx1.53 \\ \\ 
\Rightarrow h=15(1.53)-4.9(1.53)^2\;\;\;\Rightarrow h=11.48\,m$

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A sled is pulled up to the top of a hill. At thetop of the hill the sled is released from rest and allowed to coastdown the hill

Stolb23 [73]

Answer:

a.) the speed at the bottom is greater for the steeperhill

Explanation:

since the energy at the bottom of the steeper hilis greater

$mgh =\frac{1}{mv^2}$

As we can see from above that v is higher when h ishigher.

8 0

3 years ago

Water initially at 200 kPa and 300°C is contained in a piston–cylinder device fitted with stops. The water is allowed to cool at

netineya [11]

Answer:

Δu=1300kJ/kg

Explanation:

Energy at the initial state

$p_{1}=200kPa\\t_{1}=300^{o}\\u_{1}=2808.8kJ/kg(tableA-5)$

Is saturated vapor at initial pressure we have

$p_{2}=200kPa\\x_{2}=1(stat.vapor)\\v_{2}=0.8858m^3/kg(tableA-5)$

Process 2-3 is a constant volume process

$p_{3}=100kPa\\v_{3}=v_{2}=0.8858m^{3}/kg\\u_{3}=1508.6kJ/kg(tableA-5)$

The overall in internal energy

Δu=u₁-u₃

We replace the values in equation

Δu=u₁-u₃

$=2808.8kJ/kg-1508.6kJ/kg\\=1300kJ/kg$

Δu=1300kJ/kg

3 0

3 years ago

Point charges q1 and q2 are separated by a distance of 60 cm along a horizontal axis.

amm1812

Answer:

38 cm from q1(right)

Explanation:

Given, q1 = 3q2 , r = 60cm = 0.6 m

Let that point be situated at a distance of 'x' m from q1.

Electric field must be same from both sides to be in equilibrium(where EF is 0).

=> k q1/x² = k q2/(0.6 - x)²

=> q1(0.6 - x)² = q2(x)²

=> 3q2(0.6 - x)² = q2(x)²

=> 3(0.6 - x)² = x²

=> √3(0.6 - x) = ± x

=> 0.6√3 = x(1 + √3)

=> 1.03/2.73 = x

≈ 0.38 m = 38 cm = x

8 0

3 years ago

The energy transfer diagram represents the energy of a person diving into a pool.

GREYUIT [131]

The answer is A) 1000 J
According to the law of conservation of energy, the total energy before an action is always equal to the total energy after the action.
So that is, the total energy is 8000J found as potential energy, 7000J has transformed into kinetic energy, then the thermal energy should be the remaining 1000J.

Hope this helps.

6 0

3 years ago

Can you please answer these ASAP!

SVEN [57.7K]

Answer:

Let's explain this briefly.

Suppose that we have a piece of ice (this is, solid water) now we give energy to the piece of ice, so the temperature of the ice increases. There is a point where the piece of ice will start a change of phase, at this point the temperature of the ice stops increasing because all the energy we give to the ice is used in the change of phase.

Once we have a complete change of phase, the temperature can increase again, and now we will have liquid water.

If we keep increasing the temperature we will see this happen again, when we have the transition from liquid to gas.

(and a similar thing happen when we have a material in a given phase and we remove heat from the material).

In the images we can see the different changes of phase of water.

1) In the first image we can see the circle in a part where the temperature is constant, so the temperature does not change in this part, which means that there is a change of phase happening.

2) Here we have the circle in a diagonal line, so here the temperature is changing, meaning that we have an increase of temperature in this region.

3) Here we want to know what the x-axis represents, this should rerpesent the energy that is being given to the material (so in some parts we see that the temperature increases and in other parts we see that the material changes of phase)

Then here the correct option is heat over time.

4) The freezing point is the temperature in which the change of phase from liquid to solid happens (or solid to liquid).

In the graph we can see that this change of phase happens at the temperature T = -210°C

Then the correct option is -210°C (The last option)

4 0

3 years ago