Ask question

Ask question

All categories

3 years ago

14

NO ONE KNOW HOW TO DO THIS !!!!!!!!!!!!!!!!!!! HELPPPPPPPPPP, I AM DYING

1 answer:

Maksim231197 [3]3 years ago

3 0

A)Rubbing hands, Rubbing sticks
B)Rubbing rocks, Rubbing earth substances

You might be interested in

A wave has a wavelength of 10mm and a frequency of 5 hz what is the speed?

geniusboy [140]

V=fλ
v=5*0.01
Therefore v=0.05

3 0

4 years ago

Read 2 more answers

True or False. Alfred Wegener contributed greatly to the theory of plate tectonics by collecting and analyzing fossil, glacial a

bearhunter [10]

Answer:

The Answer would be True

Explanation:

8 0

2 years ago

Read 2 more answers

A dynamite blast at a quarry launches a rock straight upward, and 1.7 s later it is rising at a rate of 17 m/s. Assuming air res

Shtirlitz [24]

Answer:

(a) $v_0= 34m/s$

(b) $v=14m/s$

Explanation:

We can derive the initial speed of the rock from the equation of the speed in function of the time:

$v=v_0-gt\\\\\implies v_0=v+gt$

Using the given values for the speed at time t=1.7s, we get:

$v_0=17m/s+(9.8m/s^{2})(1.7s)=34m/s$

In words, the speed of the rock at launch is 34m/s (a).

Next, we use this to calculate the speed at t=4.9s:

$v=v_0-gt\\\\v= 34m/s-(9.8m/s^{2})(4.9s)=-14m/s$

This means that the speed of the rock at 4.9s after the launch is 14m/s (b), and the negative sign means that it is moving downwards.

3 0

3 years ago

A generator contains a coil that spins to produce an electric current. How is energy transformed by using a generator

LiRa [457]

<u>Answer </u>

Mechanical energy ⇒ Electric energy

<u>Explanation </u>

A generator is used to produce electric energy. When he coils are made to rotate/spin, is makes the mechanical part. This coils rotates inside a magnetic fields inducing current in the coils. When current starts flowing in the coils, it forms the electrical part.

So, on the generator the energy changes are from mechanical to electrical energy.

7 0

3 years ago

Given two vectors A--> = 4.20 i^+ 7.20 j^ and B--> = 5.70 i^− 2.40 j^ , find the scalar product of the two vectors A-->

Arisa [49]

Answer:

$\vec{A}\times \vec{B}=-51.12\hat{k}$

$\theta=83.2^{\circ}$

Explanation:

We are given that

$\vec{A}=4.2\hat{i}+7.2\hat{j}$

$\vec{B}=5.70\hat{i}-2.40\hat{j}$

We have to find the scalar product and the angle between these two vectors

$\vec{A}\times \vec{B}=\begin{vmatrix}i&j&k\\4.2&7.2&0\\5.7&-2.4&0\end{vmatrix}$

$\vec{A}\times \vec{B}=\hat{k}(-10.08-41.04)=-51.12\hatk}$ $\hat{k}$

Angle between two vectors is given by

$sin\theta=\frac{\mid a\times b\mid}{\mid a\mid \mi b\mid}$

Where $\theta$ in degrees

$\mid{\vec{A}}\mid=\sqrt{(4.2)^2+(7.2)^2}=8.3$

Using formula $\mid a\mid=\sqrt{x^2+y^2}$

Where x= Coefficient of unit vector i

y=Coefficient of unit vector j

$\mid{\vec{B}}\mid=\sqrt{5.7)^2+(-2.4)^2}=6.2$

$\mid{\vec{A}\times \vec{B}}\mid=\sqrt{(-51.12)^2}=51.12$

Using the formula

$sin\theta=\frac{51.12}{8.3\times 6.2}=0.993$

$\theta=sin^{-1}(0.993)=83.2$ degrees

Hence, the angle between given two vectors= $83.2^{\circ}$

7 0

4 years ago