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4 years ago

Some one please help me!!!!!!!

Physics

1 answer:

inn [45]4 years ago

6 0

D) 25N!

Under the term we have work (100J) and movement of the subject (4m).

You should find force:

A=F*s

F=A/s

F=100/4

F=25 N

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The car has a constant deceleration of 4.20 m/s^2. If its initial velocity was 24.0 m/s, how long does it take to come to a stop

nalin [4]

Answer:

The time is 5.71 sec.

Explanation:

Given that,

Acceleration $a= -4.20 m/s^2$

Initial velocity = 24.0 m/s

We need to calculate the time

Using equation of motion

v = u+at[/tex]

Where, v = final velocity

u = inital velocity

t = time

a = acceleration

Put the value into the formula

$0 =24.0 +(-4.20)\times t$

$t = \dfrac{-24.0}{-4.20}$

$t=5.71\ sec$

Hence, The time is 5.71 sec.

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4 years ago

Question 1 (1 point)

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Answer:

The work done by the frictional force is 600J.

Explanation:

The work $W$ done by the frictional force is

$W= Fd$ .

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3 years ago

How does light energy work

OLEGan [10]

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3 years ago

Read 2 more answers

1.45 L of 16°C water is placed in a refrigerator. The refrigerator's motor must supply an extra 10.7 W power to chill the water

Vika [28.1K]

Answer:

The coefficient of performance of the refrigerator is 2.251.

Explanation:

In this case, the coefficient of performance of the refrigerator ( $COP$ ), no unit, is equal to the ratio of the heat rate received from the water to the power needed to work, that is:

$COP = \frac{\dot Q_{L}}{\dot W}$ (1)

$COP = \frac{\rho\cdot V\cdot c_{w}\cdot \Delta T}{\dot W \cdot \Delta t}$ (2)

Where:

$\dot Q_{L}$ - Heat rate received from the water, in watts.

$\dot W$ - Power, in watts.

$\rho$ - Density of water, in kilograms per cubic meter.

$V$ - Volume of water, in cubic meters.

$c_{w}$ - Specific heat of water, in joules per kilogram-degree Celsius.

$\Delta T$ - Temperature change, in degrees Celsius.

$\Delta t$ - Cooling time, in seconds.

If we know that $\rho = 1000\,\frac{kg}{m^{3}}$ , $V = 1.45\times 10^{-3}\,m^{3}$ , $c_{w} = 4187\,\frac{J}{kg\cdot ^{ \circ}C}$ , $\Delta T = 10\,^{\circ}C$ , $\dot W = 10.7\,W$ and $\Delta t = 2520\,s$ , then the coefficient of refrigeration of the refrigerator is: