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4 years ago

Can you get sunburned through glass?

2 answers:

8 0

Ordinary glass absorbs 97 per cent of the UVB rays that cause sunburn and some skin cancers, and 37 per cent of the less harmful UVA radiation. This translates to a protection of about SPF30, so you canstill get burned with long enough exposure.

user100 [1]4 years ago

5 0

No glass has UV protection to keep you from a sunburn

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Which of the following means that an image is real?

DochEvi [55]

To declare an image is real you would call it “authentic”

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3 years ago

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At its widest point, the diameter of a bottlenose dolphin is 0.50 m. Bottlenose dolphins are particularly sleek, having a drag c

fiasKO [112]

Answer:

497.00977 N

3742514.97005

Explanation:

$\rho$ = Density of water = 1000 kg/m³

C = Drag coefficient = 0.09

v = Velocity of dolphin = 7.5 m/s

r = Radius of bottlenose dolphin = 0.5/2 = 0.25 m

A = Area

Drag force

$F_d=\frac{1}{2}\rho CAv^2\\\Rightarrow F_d=\frac{1}{2}\times 1000 \times 0.09(\pi 0.25^2)7.5^2\\\Rightarrow F_d=497.00977\ N$

The drag force on the dolphin's nose is 497.00977 N

at 20°C

$\mu$ = Dynamic viscosity = $1.002\times 10^{-3}\ Pas$

Reynold's Number

$Re=\frac{\rho vd}{\mu}\\\Rightarrow Re=\frac{1000\times 7.5\times 0.5}{1.002\times 10^{-3}}\\\Rightarrow Re=3742514.97005$

The Reynolds number is 3742514.97005

8 0

3 years ago

A football is kicked from ground level at an angle of 53 degrees. It reaches a maximum height of 7.8 meters before returning to

Nonamiya [84]

Answer:

1.61 second

Explanation:

Angle of projection, θ = 53°

maximum height, H = 7.8 m

Let T be the time taken by the ball to travel into air. It is called time of flight.

Let u be the velocity of projection.

The formula for maximum height is given by

$H = \frac{u^{2}Sin^{2}\theta }{2g}$

By substituting the values, we get

$7.8= \frac{u^{2}Sin^{2}53 }{2\times 9.8}$

u = 9.88 m/s

Use the formula for time of flight

$T = \frac{2uSin\theta }{g}$

$T = \frac{2\times 9.88\times Sin53 }{9.8}$

T = 1.61 second

7 0

3 years ago

a car takes 1 hour to travel 100 km along a main road and the half hour to travel 20 km along a side road what is its average sp

kolezko [41]

80 km per hour i believe. i’ll admit i’m american so we don’t use km lol, but the math should be the same. total distance = 120km, and total time = 1.5 hours. 120/1.5 = 80.

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3 years ago

Which of the following are electromagnetic waves?

olchik [2.2K]

Answer:

Microwaves

Radiowaves.

5 0

3 years ago

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