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ad-work [718]
3 years ago
12

You are standing at the top of a cliff that has a stairstep configuration. There is a vertical drop of 7 m at your feet, then a

horizontal shelf of 8 m, then another drop of 3 m to the bottom of the canyon, which has a horizontal floor. You kick a 0.87 kg rock, giving it an initial horizontal velocity that barely clears the shelf below.
1. What initial horizontal velocity v will be required to barely clear the edge of the shelf below you? The acceleration of gravity is 9.8 m/s2 . Consider air friction to be negligible. Answer in units of m/s.
2. How far from the bottom of the second cliff will the projectile land? Answer in units of m.
Physics
1 answer:
Zolol [24]3 years ago
7 0

Answer:

1. v = 6.67 m/s

2. d = 9.54 m

Explanation:

1. To find the horizontal velocity of the rock we need to use the following equation:

d = v*t \rightarrow v = \frac{d}{t}    

<u>Where</u>:

d: is the distance traveled by the rock

t: is the time

The time can be calculated as follows:

t = \sqrt{\frac{2d}{g}}

<u>Where:</u>

g: is gravity = 9.8 m/s²

t = \sqrt{\frac{2d}{g}} = \sqrt{\frac{2*7 m}{9.8 m/s^{2}}} = 1.20 s

Now, the horizontal velocity of the rock is:

v = \frac{d}{t} = \frac{8 m}{1.20 s} = 6.67 m/s      

Hence, the initial velocity required to barely reach the edge of the shell below you is 6.67 m/s.          

2. To calculate the distance at which the projectile will land, first, we need to find the time:

t = \sqrt{\frac{2d}{g}} = \sqrt{\frac{2*(7 m + 3 m)}{9.8 m/s^{2}}} = 1.43 s

So, the distance is:

d = v*t = 6.67 m/s*1.43 s = 9.54 m    

Therefore, the projectile will land at 9.54 m of the second cliff.

I hope it helps you!        

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Using a skillet on the stove to cook scrambled eggs is an example of which heat transfer?
MatroZZZ [7]

Answer: conduction.


Explanation:


1) A skillet or pan will be in direct contact with the food.


2) Being the skillet a solid matter, it transfers heat by conduction.


3) There are three heat transfer mechanisms: convection, conduction, radiation.


i) Convection: only happens in fluids: liquids and gases.


It is a slow mechanism and is due to the motion of the particles of fluid.


This is not the case, since the skillet is solid and the eggs are in direct contact with it. If the eggs were separated from the skillet convection might happen but it would be very slow and the eggs would take so long time to be cooked.


ii) Conduction: happens by direct contact among neighboring particles, due to their vibrations. The vibrations are only transmitted to neighboring particles, which is only possibble when they are in direct contact, so it is the classical mechanism in solids. So, the heat transfer using the skillet to cook scrambles eggs is an example of conduction.


iii) Radiation: is the transfer of heat by infrared waves. It is an important mechanism when the substances are separated by vaccum or gases and the difference of temperature is high. Yet, this is not the importante mechanism here. You feel heat radiation when you put your hand close to the skillet.



4 0
3 years ago
Read 2 more answers
An empty glass beaker has a mass of 103 g. When filled with water, it has a total mass of 361g.
aivan3 [116]

Answer:

0.96 gcm¯³

Explanation:

From the question given above, the following data were obtained:

Mass of empty beaker = 103 g

Mass of beaker + water = 361 g

Mass of beaker + oil = 351 g

Density of water = 1 gcm¯³

Density of cooking oil =?

Next, we shall determine the mass of water. This can be obtained as follow:

Mass of empty beaker = 103 g

Mass of beaker + water = 361 g

Mass of water =?

Mass of water = (Mass of beaker + water) – (Mass of empty beaker)

Mass of water = 361 – 103

Mass of water = 258 g

Next, we shall determine the volume of the beaker. This can be obtained by calculating the volume of water in the beaker.

Density of water = 1 gcm¯³

Mass of water = 258 g

Volume of water =?

Density = mass /volume

1 = 258 / volume

Cross multiply

1 × volume = 258

Volume of water = 258 cm³

Thus the volume of the beaker is 258 cm³.

Next, we shall determine the mass of the cooking oil. This can be obtained as follow:

Mass of empty beaker = 103 g

Mass of beaker + oil = 351 g

Mass of cooking oil =?

Mass of cooking oil = (Mass of beaker + oil) – (Mass of empty beaker)

Mass of cooking oil = 351 – 103

Mass of cooking oil = 248 g

Finally, we shall determine the density of the cooking oil. This can be obtained as follow:

Mass of cooking oil = 248 g

Volume of the beaker = 258 cm³

Density of cooking oil =?

Density = mass / volume

Density = 248 / 258

Density of cooking oil = 0.96 gcm¯³

7 0
3 years ago
Compute the dot product of the vectors u and v​, and find the angle between the vectors. Bold v equals 7 Bold i minus Bold j and
OLga [1]

Answer:

\theta = 106.3 degree

Explanation:

As we know that

\vec w = -\hat i + 7\hat j

\vec v = 7\hat i - \hat j

also we know that

\vec v. \vec w = -14

it is given as

\vec v. \vec w = (-\hat i + 7\hat j).(7\hat i - \hat j)

\vec v. \vec w = - 7 - 7 = -14

also we can find the magnitude of two vectors as

|v| = \sqrt{(-1)^2 + (7)^2}

|v| = \sqrt{50}

similarly we have

|w| = \sqrt{(7^2) + (-1)^2}

|w| = \sqrt{50}

now we know the formula of dot product as

\vec v. \vec w = |v||w| cos\theta

-14 = (\sqrt{50})^2cos\theta

\theta = cos^{-1}(\frac{-14}{50})

\theta = 106.3 degree

3 0
3 years ago
Difine scalar quantity​
vfiekz [6]

Scalar quantity are physical quantities that have just magnitude, not direction.

  • It is always positive.
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2 years ago
A 0.3-kg object connected to a light spring with a force constant of 19.3 N/m oscillates on a frictionless horizontal surface. A
Ghella [55]

The total work <em>W</em> done by the spring on the object as it pushes the object from 6 cm from equilibrium to 1.9 cm from equilibrium is

<em>W</em> = 1/2 (19.3 N/m) ((0.060 m)² - (0.019 m)²) ≈ 0.031 J

That is,

• the spring would perform 1/2 (19.3 N/m) (0.060 m)² ≈ 0.035 J by pushing the object from the 6 cm position to the equilibrium point

• the spring would perform 1/2 (19.3 N/m) (0.019 m)² ≈ 0.0035 J by pushing the object from the 1.9 cm position to equilbrium

so the work done in pushing the object from the 6 cm position to the 1.9 cm position is the difference between these.

By the work-energy theorem,

<em>W</em> = ∆<em>K</em> = <em>K</em>

where <em>K</em> is the kinetic energy of the object at the 1.9 cm position. Initial kinetic energy is zero because the object starts at rest. So

<em>W</em> = 1/2 <em>mv</em> ²

where <em>m</em> is the mass of the object and <em>v</em> is the speed you want to find. Solving for <em>v</em>, you get

<em>v</em> = √(2<em>W</em>/<em>m</em>) ≈ 0.46 m/s

8 0
3 years ago
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