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3 years ago

7

Alkaline earth metals have a low density true false

1 answer:

Marta_Voda [28]3 years ago

6 0

true

Explanation:

this is because melting point and boiling point decreases down the group because they are held together by attractions between positive nuclei and delocalised electrons

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An astronaut stands by the rim of a crater on the Moon, where the acceleration of gravity is 1.62 m/s2 and there is no air. To d

Nesterboy [21]

Answer:

12.1 seconds

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity = 0

s = Displacement = 120 m

a = Acceleration due to gravity on Moon = 1.67 m/s²

Equation of motion

$v^2-u^2=2as\\\Rightarrow -u^2=2as-v^2\\\Rightarrow -u^2=2\times -1.67\times 120-0^2\\\Rightarrow u=\sqrt{2\times 1.67\times 120}\\\Rightarrow u=20.02\ m/s$

$v=u+at\\\Rightarrow t=\frac{v-u}{a}\\\Rightarrow t=\frac{0-20.2}{-1.67}\\\Rightarrow t=12.1\ s$

Time taken by the rock to hit the bottom of the crater is 12.1 seconds

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3 years ago

What is the speed of sound in solid? <br>

sasho [114]

The speed of sound in a solid would be 6000 metres per second

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2 years ago

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A ranger in a national park is driving at 52 km/h when a deer jumps onto the road 87 m ahead of the vehicle. After a reaction ti

lys-0071 [83]

Answer:

Time, t = 0.23 seconds

Explanation:

It is given that,

Initial speed of the ranger, u = 52 km/h = 14.44 m/s

Final speed of the ranger, v = 0 (as brakes are applied)

Acceleration of the ranger, $a=-4\ m/s^2$

Distance between deer and the vehicle, d = 87 m

Let d' is the distance covered by the deer so that it comes top rest. So,

$d'=\dfrac{v^2-u^2}{2a}$

$d'=\dfrac{-(14.44)^2}{2\times -4}$

d' = 26.06 m

Distance between the point where the deer stops and the vehicle is :

D=d-d'

D=87 - 26.06 = 60.94 m

Let t is the maximum reaction time allowed if the ranger is to avoid hitting the deer. It can be calculated as :

$t=\dfrac{v}{D}$

$t=\dfrac{14.44}{60.94}$

t = 0.23 seconds

Hence, this is the required solution.

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3 years ago

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Jlenok [28]

Answer:

Quick maths

First you find the fafarick and the lalickc and the caprisum and the joinnt

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3 years ago

What is the science principle that explains magnetic fields? I need this fast, please!

bekas [8.4K]

Answer:

I literally just learned this last week and if I remember correctly it is Faraday's Law of Induction.

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2 years ago