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3 years ago

I need help with thisssss

Physics

1 answer:

Norma-Jean [14]3 years ago

3 0

1st question is False, 2nd question is True

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Describe 2 applications of surface tension

Andrews [41]

Application of surface tension:
1) A needle placed on water can be made to float due to the surface tension of water.
2) Mosquito eggs can float on water because of its surface tension.
3) Toothpaste contains soap, which reduce the surface tension and helps it spread freely in the mouth.

8 0

3 years ago

Most metals are good electrical conductors because (5 points) they hold their electrons they have a large amount of free electro

Hunter-Best [27]

Answer:

Metals are good conductors of electricity <u>because they have free electrons</u> which help in the transfer of charge from one point to another.

6 0

3 years ago

At what speed must a 0.6 kg stone be thrown in order that it has a relativistic mass of 0.76 kg? (c = 3.00 x 10^8 m/s) A) 0.6976

soldier1979 [14.2K]

Answer:

The speed of the stone is 0.6138 c.

(B) is correct option.

Explanation:

Given that,

Mass of stone m= 0.6

Relativistic mass = 0.76

We need to calculate the speed

Using formula of rest mass

$m_{r}=\dfrac{m_{0}}{\sqrt{1-\dfrac{v^2}{c^2}}}$

$v^2=(\dfrac{m_{0}^2}{m_{r}^2}-1)c^2$

Put the value into the formula

$v^2=(\dfrac{0.6^2}{0.76^2}-1)\times c^2$

$v=\sqrt{0.37673c^2}$

$v=0.6138c$

Hence, The speed of the stone is 0.6138 c.

3 0

3 years ago

A box sliding on a horizontal frictionless surface runs into a fixed spring, compressing it a distance x1 from its relaxed posit

inn [45]

Answer:twice of initial value

Explanation:

Given

spring compresses $x_1$ distance for some initial speed

Suppose v is the initial speed and k be the spring constant

Applying conservation of energy

kinetic energy converted into spring Elastic potential energy

$\dfrac{1}{2}mv^2=\dfrac{1}{2}kx_1^2----1$

When speed doubles

$\dfrac{1}{2}m(2v)^2=\dfrac{1}{2}kx_2^2----2$

divide 1 and 2

$\dfrac{1}{4}=\dfrac{x_1^2}{x_2^2}$

$x_2=2x_1$

Therefore spring compresses twice the initial value

7 0

3 years ago

When a spinning star shrinks in radius, it speeds up. Which of the following statements explains this phenomenon?

Sever21 [200]

Answer:

B.)Angular momentum is always conserved

Explanation:

Angular momentum is given by:

$L=mvr$

where

m is the mass of the object

v is its speed

r is the distance between the object and the centre of its circular trajectory

In absence of external torques, angular momentum is always conserved. That means that for the spinning star, if its radius r decreases (because it shrinks), in order for L (the angular momentum) to be conserved, the speed (v) must increases, therefore the spinning star speeds up.

So, the correct choice is

B.)Angular momentum is always conserved

4 0

3 years ago