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3 years ago

I dont know how to do question 3，4

Physics

1 answer:

dlinn [17]3 years ago

7 0

Prior to the Cambrian, organisms with hard parts (eg. shells and bones) weren't present for most the time, and it's generally such hard parts that get to fossilize. There's also been more time for Precambrian deposits to get destroyed by natural processes, 

The supply of Precambrian fossils has actually greatly improved over the last few decades. The so called Ediacaran faunas have been found at many parts of the world, and would be worth looking into.hope it helps

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The following are secondary sources of energy except a.coal b crude oil c nuclear d wind e wood

monitta

Answer:

d) Wind

Explanation:

Secondary energy is energy produced by converting energy available in its natural state in the environment. Hence Wind is a primary source not a secondary source

8 0

2 years ago

Problem One: A beam of red light (656 nm) enters from air into the side of a glass and then into water. wavelength, c. and speed

Ivanshal [37]

Answer:

Part a)

$f_w = f_g = 4.57 \times 10^{14} Hz$

Part b)

$\lambda_w = 492 nm$

$\lambda_g = 437.3 nm$

Part c)

$v_w = 2.25 \times 10^8 m/s$

$v_g = 2.0 \times 10^8 m/s$

Explanation:

Part a)

frequency of light will not change with change in medium but it will depend on the source only

so here frequency of light will remain same in both water and glass and it will be same as that in air

$f = \frac{v}{\lambda}$

$f = \frac{3 \times 10^8}{656 \times 10^{-9}}$

$f = 4.57 \times 10^{14} Hz$

Part b)

As we know that the refractive index of water is given as

$\mu_w = 4/3$

so the wavelength in the water medium is given as

$\lambda_w = \frac{\lambda}{\mu_w}$

$\lambda_w = \frac{656 nm}{4/3}$

$\lambda_w = 492 nm$

Similarly the refractive index of glass is given as

$\mu_w = 3/2$

so the wavelength in the glass medium is given as

$\lambda_g = \frac{\lambda}{\mu_g}$

$\lambda_g = \frac{656 nm}{3/2}$

$\lambda_g = 437.3 nm$

Part c)

Speed of the wave in water is given as

$v_w = \frac{c}{\mu_w}$

$v_w = \frac{3 \times 10^8}{4/3}$

$v_w = 2.25 \times 10^8 m/s$

Speed of the wave in glass is given as

$v_g = \frac{c}{\mu_g}$

$v_g = \frac{3 \times 10^8}{3/2}$

$v_g = 2 \times 10^8 m/s$

4 0

3 years ago

Two particles, one with charge −7.97×10−6 C and the other with charge 6.91×10−6 C, are 0.0359 m apart. What is the magnitude of

kolbaska11 [484]

Answer:

-384.22N

Explanation:

From Coulomb's law;

F= Kq1q2/r^2

Where;

K= constant of Coulomb's law = 9 ×10^9 Nm^2C-2

q1 and q2 = magnitudes of the both charges

r= distance of separation

F= 9 ×10^9 × −7.97×10^−6 × 6.91×10^−6/(0.0359)^2

F= -495.65 × 10^-3/ 1.29 × 10^-3

F= -384.22N

7 0

3 years ago

One watt is equal to which of these values?

dusya [7]

1 W = 1 J/s
Watt is the unit of measure for power .

Joule is the unit of measure for the energy and the second is the unit of measure for time.

3 0

3 years ago

Read 2 more answers

Velocity of a machine is always greater than mechanical advantage? why

MrRa [10]

Answer:The mechanical advantage of a machine is always less than its velocity ratio.It is because mechanical advantage decreases due to the friction and weight of moving parts of the machine, but the velocity ratio remains constant.

Explanation: hope this helps

3 0

3 years ago