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3 years ago

What is the velocity at 3 seconds?

Physics

1 answer:

Aliun [14]3 years ago

3 0

Velocity = (distance covered in a direction) / (time to cover the distance)

Since the y-axis is position (distance), the speed at 3 seconds is the slope of the graph at 3 seconds, and NOT its y-value.

The slope is fairly easy to pick off, because the graph is so straight from 2 sec to 5 sec. During that time, the distance shrinks by 10 meters (from 10m to zero). So the slope of that whole piece of the graph is (-10m) / (3 sec).

That's a slope of (10/3 m/s) or 3.33 m/s .

In answer to the question, we can only give the speed at 3 sec, not the velocity, since we have no information about the direction of the motion. Consequently, I would call the speed a positive number. But it's not worth arguing about, so you should just select <em>choice-A </em>and not make a big scene.

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A student is planning an experiment to find

mamaluj [8]

Answer:

b) the height the ball bounces

Explanation:

the control variable is the variable that you change yourself. since you change the height that the ball bounces from we know this is the answer

4 0

3 years ago

Read 2 more answers

The Law of Reflection states that the Angle of Incidence will always be

VladimirAG [237]

Answer: option c) equal to the angle of reflection.

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3 years ago

For heat transfer purposes, an egg can be considered to be a 5.5-cm-diameter sphere having the properties of water. An egg that

Harrizon [31]

Answer:

The time taken is $t = 40007 sec$

Explanation:

From the question we are told that

The diameter of the egg is $d_e = 5.5cm = \frac{5.5}{100} = 5.5*10^{-2}m$

The initial temperature of egg the $T_e = 4.3^{o}C$

The temperature of the boiling water $T_b = 100^oC$

The heat transfer coefficient is $H = 800 W/m^2 \cdot K$

The final temperature is $T_e_f = 74^oC$

The thermal conductivity of water is $k = 0.607 W/m^oC$

The diffusivity of the egg $\alpha = 0.146 * 10^{-6} m^2 /s$

Using one term approximation

We have the

$\frac{T_e_f - T_b}{T_e - T_b} = Ae^{-\lambda ^2 \tau}$

The radius is $r = \frac{5.5*10^ {-2}}{2} =2.75*10^{-2}m$ Note that this radius is approximation to that of a real egg

Now we need to obtain the Biot number which help indicate the value of $A \ and \ \lambda$ to use in the above equation

The Biot number is mathematically represented as

$Bi = \frac{H r}{k}$

Substituting values

$Bi = \frac{800 * 2.75 *10^{-2}}{0.607}$

$= 36.24$

So for this value which greater than 0.1 the coefficient $\lambda_1 \ and \ A_1$ is

$\lambda = 3.06632$

$A = 1.9942$

Substituting this into equation 1 we have

$\frac{74- 100}{4.3 - 100} = 1.9942 e^{-(3.0632^2) \tau}$

$0.2717= 1.9942 e^{-(3.0632^2) \tau}$

$0.2717= 1.9942 e^{-9.383 \tau}$

$0.13624 = e^{-9.383 \tau}$

Taking natural log of both sides

$-1.993 = -9.383\ \tau$

$\tau = 0.2124$

The time required for the egg to be cooked is mathematically represented as

$t = \frac{\tau r^2}{\alpha }$

substituting value is

$= \frac{0.2124 * 2.75 *10^{-2}}{0.146 *10^{-6}}$

$t = 40007 sec$

8 0

3 years ago

A boat moves with a speed of +2.5 m/s in a direction 25° north of east. If the mass of the boat is 15,000 kg, what is the moment

nadya68 [22]

Momentum - mass in motion
P=MV
P=(15,000 kg)(2.5 m/s)
P=37 500 kg x m/s to the north
Hope this helps

5 0

3 years ago

Dumbo the elephant weights 13,000 pounds. What force would the Earths surface apply to Dumbo? 2.2 pounds = 1 kg

snow_lady [41]

Answer:

57908 N

Explanation:

Let's first convert Dumbo's mass into kg using the given relationship: 2.2 pounds =1 kg.

Then, 13000 lbs = 13000/2.2 kg = 5909 kg

Now, let's find the force of gravity on Dumbo at the surface of the earth, which would be in magnitude equal to the normal force that the Earth's surface applies on Dumbo.

F = m * a = 5909 kg * 9.8 m/s^2 = 57908 N

8 0

3 years ago