All categories

3 years ago

Explain why the moon is always half illuminated and half dark no matter where it is in the lunar cycle.

1 answer:

7 0

The easiest way I know to explain it is this:

-- Take a flashlight and a ball into a dark room.

-- Turn on the flashlight and point it at the ball.

-- Half of the ball is lighted up by the flashlight, and the other half is dark.

-- There is no way you can turn or twist the ball to make more or less
than 50% of it lighted up and more or less than 50% of it dark.

Everything in the solar system ... as long as it's shaped like a ball ... is
half illuminated by the sun and half dark.

You might be interested in

The displacement of body is proportional to cube of time then body is uniform

seropon [69]

This doesn’t make sense

7 0

4 years ago

A train is moving in a straight railway where it covered one third of the distance with

Alexxandr [17]

Answer:

The average speed of the train is 45 km/h

Explanation:

Speed

It's defined as the distance (d) per unit of time (t) traveled by an object. The formula is:

$\displaystyle v=\frac{d}{t}$

Let's call x the total distance covered by the train. It covered d1=1/3x with a speed of v1=25 km/h. The time taken is calculated solving for t:

$\displaystyle t_1=\frac{d_1}{v_1}$

$\displaystyle t_1=\frac{1/3x}{25}$

$\displaystyle t_1=\frac{x}{75}$

Now the rest of the distance:

d2 = x - 1/3x = 2/3x

Was covered at v2=75 km/h. Thus the time taken is:

$\displaystyle t_2=\frac{d_2}{v_2}$

$\displaystyle t_2=\frac{2/3x}{75}$

$\displaystyle t_2=\frac{2x}{225}$

The total time is:

$\displaystyle t_t=\frac{x}{75}+\frac{2x}{225}$

$\displaystyle t_t=\frac{3x}{225}+\frac{2x}{225}$

$\displaystyle t_t=\frac{5x}{225}$

Simplifying:

$\displaystyle t_t=\frac{x}{45}$

The average speed is the total distance divided by the total time:

$\displaystyle \bar v=\frac{x}{\frac{x}{45}}$

Simplifying:

$\boxed{\displaystyle \bar v=45\ km/h}$

The average speed of the train is 45 km/h

5 0

3 years ago

A charging bull elephant with a mass of 5240 kg comes directly toward youwith a speed of 4.55 m/s. You toss a 0.150- kg rubber b

bearhunter [10]

Answer:

Explanation:

mass of elephant, m1 = 5240 kg

mass of ball, m2 = 0.150 kg

initial velocity of elephant, u1 = - 4.55 m/s

initial velocity of ball, u2 = 7.81 m/s

Let the final velocity of ball is v2.

Use the formula of collision

$v_{2}=\left ( \frac{2m_{1}}{m_{1}+m_{2}} \right )u_{1}+\left ( \frac{m_{2}-m_{1}}{m_{1}+m_{2}} \right )u_{2}$

$v_{2}=\left ( \frac{2\times 5240}{5240+0.150} \right )(-4.55)+\left ( \frac{0.15-5240}{5240+0.150} \right )(7.81)$

v2 = - 16.9 m/s

The negative sign shows that the ball bounces back towards you.

(b) It is clear that the velocity of ball increases and hence the kinetic energy of the ball increases. This gain in energy is due to the energy from elephant.

5 0

4 years ago

A kettle does 1 J of work in 1 second. What is the power of the kettle?

iris [78.8K]

Answer:

The power of the kettle is P = 1 watt.

Explanation:

The definition of power is:

Power equals the quotient between work and time, or:

P = w/t.

In this case, we know that the work is:

w = 1J

And the time is:

t = 1 s

Then the power will be:

P = 1J/1s = 1 J/s

Also knowing that:

1 J/s = 1 W

(w is the unit for Watt)

We can conclude that the power of the kettle is:

P = 1 W

8 0

3 years ago

If you lift one load up two stories, how much work do you do compared to lifting one load up only one story?

Tatiana [17]

Answer:

D)Twice as much

Explanation:

Work: This is the product of force and distance along the direction of the force. The S. I unit of work is Joules (J)

Energy: Energy is the ability or the capacity to perform work. Energy and work can be interchange during calculation.

E = W = mgh.................................... Equation 1

Where m = mass of the load, h = height of one story, g = acceleration due to gravity.

constant: g = 9.8 m/s²

When the load is lift up only one story

W = 9.8mh..................... Equation 2

But when the load is lifted through two story,

height = 2h

W = 19.6mh .................... Equation 3

Comparing Equation 2 and equation 3,

It shows that the work done to lift the load up two story is twice the work done to lift the load up one story.

The right option is D)Twice as much

7 0

4 years ago