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2 years ago

5

A ball falls from a shelf. Assuming there is no friction, why is the conservation of mechanical energy independent of mass?(1 po

int)
The displacement of the ball is insignificant compared with Earth's size.

The mass of the ball is insignificant compared with the mass of Earth.

Mass is eliminated when equating elastic potential energy with kinetic energy.

Mass is eliminated when equating gravitational potential energy with kinetic energy.

2 answers:

Leya [2.2K]2 years ago

7 0

Answer: C

Explanation: Mass is eliminated when equating elastic potential energy with kinetic energy.

cluponka [151]2 years ago

5 0

Answer:

It's B

Explanation:

Hope this helps, tell me if im wrong!

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for an object that is speeding up in the positive direction what does the displacement vs. time graph look like

avanturin [10]

For an object that is speeding up in the positive direction, its positive displacement is greater every second, and the AMOUNT greater every second is greater than the AMOUNT greater was in the previous second.

So the graph of displacement vs. time is rising as time goes on, and the rise is becoming steeper as time goes on.

The graph is <em>curving upward</em> as time goes on.

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3 years ago

The motor in a refrigerator has a power output of 400 W. If the freezing compartment is at 273 K and the outside air is at 306 K

Aleksandr [31]

Answer:15,883.63 KJ

Explanation:

Given

Power=400 W

Freezing compartment temperature is 273 K $(T_L)$

Outside air Temperature=306 K $(T_H)$

Time =80 minutes

Energy Required to deliver 400 w power in 80 minutes

E=1920 KJ

and we know COP of refrigerator is given by

$COP=\frac{T_L}{T_H-T_L}$ $=\frac{Desired\ effect}{Work}$

$\frac{273}{306-273}=\frac{D.E.}{1920}$

$D.E.=8.27\times 1920=15883.63 KJ$

Therefore 15,883.63 KJ is removed in 80 minutes

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3 years ago

A chemical reaction occurs. Which of the following would indicate that energy is transformed during the reaction?

weqwewe [10]

The answer would be 4. All of the above

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3 years ago

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Two cars leave Calgary at the same time, travelling in opposite directions. Their average speeds differ by 5 km/h. After 2 h, th

dimulka [17.4K]

Let the first car's average speed be x

The second car's speed would be x+5

$2(x+(x+5))=210$

$2x+5=105$

$2x=100$

$x=50$

So the speed of the slower car is 50mph, and the speed of the faster car is 55mph

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3 years ago

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A 2.00 kg block hangs from a spring balance calibrated in Newtons that is attached to the ceiling of an elevator.(a) What does t

tresset_1 [31]

Answer:

Part a)

$Reading = 2.00 kg$

Part b)

$Reading = 2.00 kg$

Part c)

$Reading = 4.04 kg$

Part d)

from t = 0 to t = 4.9 s

so the reading of the scale will be same as that of weight of the block

Then its speed will reduce to zero in next 3.2 s

from t = 4.9 to t = 8.1 s

The reading of the scale will be less than the actual mass

Explanation:

Part a)

When elevator is ascending with constant speed then we will have

$F_{net} = 0$

$T - mg = 0$

$T = mg$

So it will read same as that of the mass

$Reading = 2.00 kg$

Part b)

When elevator is decending with constant speed then we will have

$F_{net} = 0$

$T - mg = 0$

$T = mg$

So it will read same as that of the mass

$Reading = 2.00 kg$

Part c)

When elevator is ascending with constant speed 39 m/s and acceleration 10 m/s/s then we will have

$F_{net} = ma$

$T - mg = ma$

$T = mg + ma$

Reading is given as

$Reading = \frac{mg + ma}{g}$

$Reading = 2.00\frac{9.81 + 10}{9.81}$

$Reading = 4.04 kg$

Part d)

Here the speed of the elevator is constant initially

from t = 0 to t = 4.9 s

so the reading of the scale will be same as that of weight of the block

Then its speed will reduce to zero in next 3.2 s

from t = 4.9 to t = 8.1 s

The reading of the scale will be less than the actual mass

3 0

3 years ago