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3 years ago

A convex lens can produce a real image but not a viral image a. true b. false

Physics

1 answer:

serious [3.7K]3 years ago

5 0

The answer is true a convex lens can produce a real image but not a viral image

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An 8-hour exposure to a sound intensity level of 90.0 dB may cause hearing damage. What energy in joules falls on a 0.800-cm-dia

11111nata11111 [884]

Answer:

1.4E-3J

Explanation:

Given that

Time = 8hrs = 28.8E3 seconds

Intensity= 90dB

D= 0.008m

Radius= 0.004m

So intensity is sound level Bis

10dBlog(I/Io)

I= 10 (B/10dB)Io

= 10( 90/10) x 10^-12

=0.001W/m²

But we know that

I = P/A

P= I πr²

= 5.02 x10^-8W

But energy is power x time

So E= 5.02E-8 x 28.8E3

= 1.4E-3J

5 0

3 years ago

Read 2 more answers

The electric force between two charged balloons is 0.12 newtons. If the distance between the two balloons is halved, what will b

marshall27 [118]

Answer:

The answer is D, I just took the test

Explanation:

5 0

3 years ago

It was a dark and stormy night, when suddenly you saw a flash of lightning. Three-and-a-half seconds later you heard the thunder

Gekata [30.6K]

We're going to multiply the time it took for you to hear thunder (3.5 seconds) by the speed of sound in air (340 m/s)

3.5 x 340 = 1190

The lightning bolt was 1,190 meters away.

3 0

3 years ago

1) A force of 157 N is applied to a box 25o above the horizontal. If it is applied over a distance of 14.5 m how much work is do

vfiekz [6]

Work done is given by

$W = F.d cos\theta$

here we know that

F = 157 N

d = 14.5

$\theta = 25^0$

now from the above formula

$W = (157)(14.5)cos25 = 2063.2 J$

By energy conservation

Initial total potential energy of egg = final total kinetic energy of egg

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

$v = \sqrt{2gh}$

$v = \sqrt{2(9.8)(8.2)}$

$v = 12.7 m/s$

By momentum conservation we know that

$m_1v_1 = (m_1 + m_2)v$

$215(9.5) = (215 + 19.7) v$

$v = \frac{215 (9.5)}{215 + 19.7}$

$v = 8.7 m/s$

by momentum conservation we know that

$m_1v_1 + m_2v_2 = (m_1 + m_2) v$

let direction of velocity of Jay Z car motion is positive direction

now we will say

$1100(-20) + 1475v = (1100 + 1475)(7)$

$1475 v = 2575(7) + 1100(20)$

$v = 27.14 m/s$

Yes Jay Z is overspeeding as his speed is more than speed limit

Tension force in the string will be centripetal force

so here we can say

$T = \frac{mv^2}{R}$

here we know that

m = 0.63 kg

v = 7.8 m/s

R = 0.23 m

$T = \frac{0.63 (7.8)^2}{0.23}$

$T = 166.6 N$

6 0

3 years ago

Why did Copernicus want to develop a completely new system for predicting planetary positions? Provide two reasons.

LiRa [457]

Answer:

1) improve the quality of data

2) new system is more simple and elegant

Explanation:

the reason for being selected new system of determining planetary positions are

1) he want to improve the quality of data for having new planetary positioned value.

b) he believed that new system is more simple and elegant for determining planetary positions by both skilled and unskilled user i.e. astronomers and general public

7 0

3 years ago