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3 years ago

Answer pls will give 20 points per person

Physics

2 answers:

LuckyWell [14K]3 years ago

7 0

Answer: question 1 is b I believe

Explanation:

every action has an opposite reaction

pogonyaev3 years ago

5 0

Answer:

Mscalculator is right it is "B" i took it on edge

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John has a boat that will travel at the rate of 15 kph in still water. he can go upstream for 35 km in the same time it takes to

MA_775_DIABLO [31]

Let F = the downstream speed of the water.

Then the boat's upstream speed is: 15 - F 
The boat's downstream speed is: 15 + F 

Assume both the journeys mentioned take T hours, then using "speed x time = distance" we get: 

Downstream journey: (15 + F)T = 140 
Upstream journey: (15 - F)T = 35 

Add the two formulae together: 

(15 + F)T + (15 - F)T = 140 + 35 

15T + FT + 15T - FT = 175 

30T = 175 

T = 35/6 

Use one of the equations to find F: 

(15 + F)T = 140 

15 + F = 140/T 
F = 140/T - 15 
F = 140/(35/6) - 15 
F = 24 - 15 
F = 9 

i.e. the downstream speed of the water is 9 kph 

Therefore, the boat's speed downstream is 15 + F = 15 + 9 = 24 kph.
the answer is: *24kph*

5 0

3 years ago

If an object has zero acceleration, does it have to have zero velocity?

adelina 88 [10]

Answer:

Yes, the velocity would also be zero.

Explanation:

Acceleration is the change in velocity over time, therefore, there has to be a change in velocity for something to accelerate. which means without acceleration, the object has no velocity.

3 0

3 years ago

In a science fiction novel two enemies, Bonzo and Ender, are fighting in outer spce. From stationary positions, they push agains

Hoochie [10]

Answer:

$\frac{m_B}{m_E}=1.18$

Explanation:

$m_B$ = Mass of Bonzo

$m_E$ = Mass of Ender

$u_B$ = Initial Velocity of Bonzo = 2.2 m/s

$u_E$ = Initial Velocity of Ender = -2.6 m/s

From conservation of linear momentum

$m_Bu_B=m_Eu_E\\\Rightarrow \frac{m_B}{m_E}=\frac{u_E}{u_B}\\\Rightarrow \frac{m_B}{m_E}=\frac{2.6}{2.2}\\\Rightarrow \frac{m_B}{m_E}=1.18$

$\therefore \frac{m_B}{m_E}=1.18$

8 0

3 years ago

A common method to measure thermal conductivity of a biomaterial is to insert a long metallic probe axially into the center of a

tia_tia [17]

Answer:

The thermal conductivity of the biomaterial is approximately 1.571 watts per meter-Celsius.

Explanation:

Let suppose that thermal conduction is uniform and one-dimensional, the conduction heat transfer ( $\dot Q$ ), measured in watts, in the hollow cylinder is:

$\dot Q = \frac{2\cdot k\cdot L}{\ln \left(\frac{D_{o}}{D_{i}} \right)}\cdot (T_{i}-T_{o})$

Where:

$k$ - Thermal conductivity, measured in watts per meter-Celsius.

$L$ - Length of the cylinder, measured in meters.

$D_{i}$ - Inner diameter, measured in meters.

$D_{o}$ - Outer diameter, measured in meters.

$T_{i}$ - Temperature at inner surface, measured in Celsius.

$T_{o}$ - Temperature at outer surface, measured in Celsius.

Now we clear the thermal conductivity in the equation:

$k = \frac{\dot Q}{2\cdot L\cdot (T_{i}-T_{o})}\cdot \ln\left(\frac{D_{o}}{D_{i}} \right)$

If we know that $\dot Q = 40.8\,W$ , $L = 0.6\,m$ , $T_{i} = 50\,^{\circ}C$ , $T_{o} = 20\,^{\circ}C$ , $D_{i} = 0.01\,m$ and $D_{o} = 0.04\,m$ , the thermal conductivity of the biomaterial is: