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Xelga [282]
4 years ago
12

Picture showing four cards in a row with labels 'First animal appears on land', 'First life form appears in the sea', 'First roc

ks formed on Earth', and 'First flowering plants appear on land'.
A student arranged the four cards sequentially in a row on the basis of the periods when the events occurred. The card showing the earliest event was placed on the extreme left. Which of these cards was placed first in the row?
Physics
1 answer:
sasho [114]4 years ago
3 0
The answer would be 'First rocks formed on Earth'.
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Crank

F = ma

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3 years ago
Why is the pipe that carries the heated glycol from the box to the tank at an angle?​
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3 years ago
A uniform meterstick of mass 0.20 kg is pivoted at the 40 cm mark. where should one hang a mass of 0.50 kg to balance the stick?
Tcecarenko [31]
The weight of the meterstick is:
W=mg=0.20 kg \cdot 9.81 m/s^2 = 1.97 N
and this weight is applied at the center of mass of the meterstick, so at x=0.50 m, therefore at a distance 
d_1 = 0.50 m - 0.40 m=0.10 m
from the pivot.
The torque generated by the weight of the meterstick around the pivot is:
M_w = W d_1 = (1.97 N)(0.10 m)=0.20 Nm

To keep the system in equilibrium, the mass of 0.50 kg must generate an equal torque with opposite direction of rotation, so it must be located at a distance d2 somewhere between x=0 and x=0.40 m. The magnitude of the torque should be the same, 0.20 Nm, and so we have:
(mg) d_2 = 0.20 Nm
from which we find the value of d2:
d_2 =  \frac{0.20 Nm}{mg}= \frac{0.20 Nm}{(0.5 kg)(9.81 m/s^2)}=0.04 m

So, the mass should be put at x=-0.04 m from the pivot, therefore at the x=36 cm mark.
4 0
4 years ago
Suppose the maximum safe intensity of microwaves for human exposure is taken to be 1.39~\mathrm{W/m^2}1.39 W/m ​2 ​​ . If a rada
wolverine [178]

Answer:

0.763 m

Explanation:

Intensity I = power P ÷ area A of exposure (spherical area of propagation)

I = P/A

A = P/I

Power = 10.0 W

Intensity = 1.39 W/m^2

A = 10/1.39 = 7.19 m^2

Area A = 4¶r^2

7.19 = 4 x 3.142 x r^2

7.19 = 12.568r^2

r^2 = 7.19/12.568 = 0.57

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3 0
3 years ago
A particle beam is made up of many protons, each with a kinetic energy of 3.25times 10-15 J. A proton has a mass of 1.673 times
ArbitrLikvidat [17]

Answer:

The magnitude of a uniform electric field that will stop these protons in a distance of 2 m is 1.01 x 10^{-4} N/C

Explanation:

given information,

kinetic energy, KE = 3.25 x 10^{-15} J

proton's mass, m = 1.673 x 10^{-27} kg

charge, q = 1.602 x 10^{-19} C

distance, d = 2 m

to find the electric field that will stop the proton, we can use the following equation:

E = F/q

   = (KE/d) / q ,        KE = Fd --> F = KE/d

   = KE/qd

    = (3.25 x 10^{-15} J) / (1.602 x 10^{-19} C)(2 m)

    = 1.01 x 10^{-4} N/C

3 0
3 years ago
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