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JulijaS [17]
3 years ago
11

1. Johnny wants to know where the water line is in a dark well. He drops a penny into the well and counts until he hears the pen

ny hit the water. He counts exactly 3 seconds. How far down is the water line?
Physics
1 answer:
777dan777 [17]3 years ago
8 0

Answer:

3 feet down

Explanation:

i think

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Suppose of methane are burned in air at a pressure of exactly and a temperature of . Calculate the volume of carbon dioxide gas
Licemer1 [7]

There are supposed to be numbers in these places:

" _____ of methane"

" ... pressure of exactly _____ "

" ... temperature of _____ "

I've seen a lot of questions with missing numbers before, but I think this is the first time I ever saw a question where even the number of significant digits to round the answer to is missing.

"Round your answer to _____ significant digits."

4 0
3 years ago
car 2 has a mass of 150 kg and moves westward towards car 3 at a velocity of 2.2 m/s. car 3 has a mass of 265 kg and moves eastw
sergejj [24]

Answer:

The force of car 3 on car 2 ≈ 1810.82 N

Explanation:

The equation for the change in momentum of the two cars are;

Conservation of linear momentum

150( 2.2 - v) = 265(1.5-v)

150 × 2.2 - 265×1.5 = (150+265)v

150 × 2.2 - 265×1.5 = -67.5 = 415×v

∴ v = -67.5/415 = -0.1627 m/s West = 0.1627 m/s East

The impulse of the net force is the amount of momentum change experienced given by the equation;

Impulse force = m \times  v_f - m \times  v_0

Where;

v_f = The final velocity

v_0 = The initial velocity

For the the 265 kg mass, we have;

v_f = 0.1627 m/s

v_0 = 1.5 m/s

Which gives the impulse a s F×Δt =  265×0.1627 - 265×1.5 = -354.38 kg·m/s

The change in kinetic energy of the collision = 1/2×265×(0.1627^2 - 1.5^2) =-294.62 J

Whereby the distance moved in one second is 0.1627 m, we have;

Work done = Force × Distance = Force × 0.1627 = 294.62

Force = 294.62/0.1627 = 1810.82 N.

8 0
3 years ago
Which of the following is a true statement for a child's toy spinning in a circle at constant speed?
exis [7]

Answer:

The answer is C.

Explanation:

4 0
3 years ago
Read 2 more answers
Aconstant current of 3 Afor 4 hours is required to charge an automotive battery. If the terminal voltage is V, where t is in hou
kirza4 [7]

Answer:

(a) 43.2 kC

(b) 0.012V kWh

(c) 0.108V cents

Explanation:

<u>Given:</u>

  • i = current flow = 3 A
  • t = time interval for which the current flow = 4\ h = 4\times 3600\ s = 14400\ s
  • V = terminal voltage of the battery
  • R = rate of energy = 9 cents/kWh

<u>Assume:</u>

  • Q = charge transported as a result of charging
  • E = energy expended
  • C = cost of charging

Part (a):

We know that the charge flow rate is the electric current flow through a wire.

\therefore i = \dfrac{Q}{t}\\\Rightarrow Q =it\\\Rightarrow Q = 3\times 14400\\\Rightarrow Q = 43200\ C\\\Rightarrow Q = 43.200\ kC\\

Hence, 43.2 kC of charge is transported as a result of charging.

Part (b):

We know the electrical energy dissipated due to current flow across a voltage drop for a time interval is given by:

E = Vit\\\Rightarrow E = V\times 3\times 4\\\Rightarrow E = 12V\ Wh\\\Rightarrow E = 0.012V\ kWh\\

Hence, 0.012V kWh is expended in charging the battery.

Part (c):

We know that the energy cost is equal to the product of energy expended and the rate of energy.

\therefore \textrm{Cost}=\textrm{Energy}\times \textrm{Rate}\\\Rightarrow C = ER\\\Rightarrow C = 0.012V\times 9\\\Rightarrow C =0.108V\ cents

Hence, 0.108V cents is the charging cost of the battery.

4 0
4 years ago
A ball is thrown up in the air. When it falls back down and reaches the ground, it's final downward velocity is 8.0 m/s. What wa
hram777 [196]
Given : Time taken to reach the maximum height t=3 s a=−g=−10m/s
2


The initial velocity of the ball can be calculated by,
Using v=u+at
∴ 0=u−10×3 ⟹u=30 m/s

Using S=ut+
2
1
​
at
2

∴ S=30×3+
2
1
​
×(−10)×3
2
=45m
8 0
3 years ago
Read 2 more answers
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