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Semenov [28]
3 years ago
12

Please help, it's grade 7 science. :)

Physics
2 answers:
ANTONII [103]3 years ago
5 0
I just checked the other persons work and it’s correct you should use their work I was just checking if it was right and if I needed to correct anything
xeze [42]3 years ago
4 0

Answer:

The air in the soccer ball in cold weather will decrease slightly in size and it becomes flat. The air in the soccer ball in hot weather will seem flat because the low preasure leads to lower bounce in the ball.

The metal door frame in cold weather contracts and the wood contracts more in the winter. The metal door frame in hot weather thermal blowing can occur on the outer surface of the metal door frame. Hopefully that is what you were looking for have a good day.

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An astronaut on the moon drops a feather from rest (v = 0). The acceleration due to gravity is 1.67 m/s​ 2​ . If the feather beg
olga_2 [115]

Given :

Initial velocity , u = 0 m/s .

Acceleration due to gravity on moon , g_m=1.67\ m/s^2 .

Height , h = 2 m .

To Find :

Final position after falling for 1.5 seconds .

Solution :

We know , by equation of motion :

s=ut+\dfrac{at^2}{2}

Here , a = g_m .

So , equation will transform by :

s=ut+\dfrac{g_mt^2}{2}\\\\s=0+\dfrac{1.67\times 1.5^2}{2}\ m\\\\s=1.88\ m

Therefore , the height form moon's surface is 1.88 m .

Hence , this is the required solution .

6 0
3 years ago
A uniform rod of mass 3.30×10−2 kg and length 0.450 m rotates in a horizontal plane about a fixed axis through its center and pe
Alex73 [517]

(a) 2.75 rev/min

The moment of inertia of the rod rotating about its center is:

I_R=\frac{1}{12}ML^2

where

M=3.30\cdot 10^{-2} kg is its mass

L = 0.450 m is its length

Substituting,

I_R=\frac{1}{12}(3.30\cdot 10^{-2})(0.450)^2=5.57\cdot 10^{-4} kg m^2

The moment of inertia of the two rings at the beginning is

I_r = 2mr^2

where

m = 0.200 kg is the mass of each ring

r=5.20\cdot 10^{-2} m is their distance from the center of the rod

Substituting,

I_r=2(0.200)(5.20\cdot 10^{-2})^2=1.08\cdot 10^{-3} kg m^2

So the total moment of inertia at the beginning is

I_1=I_R+I_r = 5.57\cdot 10^{-4}+1.08\cdot 10^{-3}=1.64\cdot 10^{-3}kg m^2

The initial angular velocity of the system is

\omega_1 = 35.0 rev/min

The angular momentum must be conserved, so we can write:

L=I_1 \omega_1 = I_2 \omega_2 (1)

where I_2 is the moment of inertia when the rings reach the end of the rod; in this case, the distance of the ring from the center is

r=\frac{0.450 m}{2}=0.225 m

so the moment of inertia of the rings is

I_r=2(0.200)(0.225)^2=0.0203 kg m^2

and the total moment of inertia is

I_2 = I_R + I_r =5.57\cdot 10^{-4} + 0.0203 = 0.0209 kg m^2

Substituting into (1), we find the final angular speed:

\omega_2 = \frac{I_1 \omega_1}{I_2}=\frac{(1.64\cdot 10^{-3})(35.0)}{0.0209}=2.75 rev/min

(b) 103.0 rev/min

When the rings leave the rod, the total moment of inertia is just equal to the moment of inertia of the rod, so:

I_2 = I_R = 5.57\cdot 10^{-4}kg m^2

So using again equation of conservation of the angular momentum:

L=I_1 \omega_1 = I_2 \omega_2

We find the new final angular speed:

\omega_2 = \frac{I_1 \omega_1}{I_2}=\frac{(1.64\cdot 10^{-3})(35.0)}{5.57\cdot 10^{-4}}=103.0 rev/min

7 0
3 years ago
Will give BRAINEST to the person who answers right
Nookie1986 [14]
The answer of this question is B. 22x + 20
3 0
4 years ago
Read 2 more answers
What is the opposition to the flow of AC produced by a magnetic field with generated back voltage (EMF) called?
jek_recluse [69]

Answer and Explanation :

The opposition of the flow of alternating current produced by a magnetic field is called inductive reactance it is denoted by X_L, The value of the inductive reactance depends on the value of inductance. The good thing about inductive reactance is that it is not responsible for the power loss as  resistance is responsible for the power loss  

5 0
4 years ago
Can someone help pls!!
stiks02 [169]

Answer:

Rp = 10 Ohms; I = 0.9 Amps

Explanation:

Since, there are two resistors each with 20Ω connected in parallel, the total resistance of the combination (Rp) of the circuit is as follows:

i.e 1/Rp = (1/R1 + 1/R2)

1/Rp = (1/20Ω + 1/20Ω)

1/Rp = (1 + 1)/20Ω

1/Rp = 2/20Ω

1/Rp = 1/10Ω

To get the value of Rp, cross multiply

Rp x 1 = 10Ω x 1

Rp = 10Ω

Apply the formula

Voltage V = Current I x Total resistance Rp

I = V/Rp

I = 9V/10Ω

I = 0.9 Amps

Thus, the total resistance is 10 Ohms, the current through the ammeter is 0.9 Amps

8 0
3 years ago
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