The Energy Security Act of 2007 mandates that cars will become more energy efficient by the year 2020.

Savanna regions developed during the Triassic period.

stich3 [128]

The answer is : true

5 0

1 year ago

In this lab, you will use a falling cylinder attached to a propeller in a water bath to explore the conversion of energy in a sy

Tema [17]

Answer:How is potential energy converted to thermal energy in a system?

Explanation:

3 0

3 years ago

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name the device used often to change the resistance without changing the voltage source in an electric circuit

timofeeve [1]

<em>the devices which are used to change the resistance in a circuit are called
<u>resisitors...
</u>the fact that they effect the voltage or not simply depends upon the type of resistor used in the circuit ...:)

</em>

5 0

3 years ago

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Please help, I don’t get the question.

aalyn [17]

All you have to do is get the culmative effect of the forces by predicting the direction in which each object will move. Just write down what you know and put down questions for your teacher.

6 0

3 years ago

A block with a mass of 31.8 kg is pushed on a frictionless

OlgaM077 [116]

Answer: Total work done on the block is 3670.5 Joules.

Step by step:

Work done:

$W = F.d.\cos\theta$

With F the force, d the displacement, and theta the angle of action (which is 0 since the block is pushed along the direction of displacement, and cos 0 = 1)

$W = F.d$

Given:

F = 75 N

m = 31.8 kg

Final velocity $v_f = 15.3 \frac{m}{s}$

In order to calculate the Work we need to determine the displacement, or distance the block travels. We can use the information about F and m to first figure out the acceleration:

$F = ma\\\implies a=\frac{F}{m}=\frac{75 N }{31.8 kg}\approx 2.36 \frac{m}{s^2}\\$

Now we can determine the displacement from the following formula:

$d = \frac{1}{2}a^2+v_0t+d_0$

Here, the initial displacement is 0 and initial velocity is also 0 (at rest):

$d = \frac{1}{2}at^2\\$

Now we still have "t" as unknown. But we are given one more bit of information from which this can be determined:

$v_f = a\cdot t_f\\\implies t_f = \frac{v_f}{a} = \frac{15.2 \frac{m}{s}}{2.36 \frac{m}{s^2}}\approx 6.44 s$

(using vf as final velocity, and tf as final time)

So it takes about 6.44 seconds for the block to move. This allows us to finally calculate the displacement:

$d = \frac{1}{2}at^2=\frac{1}{2}2.36 \frac{m}{s^2}\cdot 6.44^2 s^2 \approx 48.94 m$

and the corresponding work:

$W = F\cdot d=75 N\cdot 48.94 m =3670.5J$

7 0

3 years ago