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4 years ago

Which of the following objects works by burning fuel to push hot air toward the ground and create thrust to use in lifting off?

2 answers:

8 0

So the choices are A. rocket B. space probe C. space station D. All of the above

Strictly speaking, only the rocket would burn fuel and create thrust to lift off. A space probe and a space station are launched into space by sitting on top of a rocket. They do not have enough fuel to lift off by themselves.

So I say the ans should be A.

olga_2 [115]4 years ago

6 0

Rockets, space stations, space probe

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if you exert 10.0 N of force to compress a spring 50 cm from its equilibrium point, then what is the spring constant?

Olegator [25]

The answer would be: b. The spring constant is 20 N/m

4 0

3 years ago

When the moon slowly moves away from the earth.How is it affecting the gravitational force between the earth and the moon?

sukhopar [10]

Well, think about how the tides will be affected when the moon moves farther away. If the moon first started off very close the earth, we would have more tsunamis. (Scientists have found that the moon has possibly been closer to earth long ago.) While it moves away, soon there will no longer be many tides.

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3 years ago

One strategy in a snowball fight is to throw a snowball at a high angle over level ground. While your opponent is watching the f

Andreas93 [3]

Answer:

Part a)

$\theta_2 = 15 degree$

Part b)

$\Delta t = 2.88 s$

Explanation:

Part a)

In order to have same range for same initial speed we can say

$R_1 = R_2$

$\frac{v^2 sin2\theta_1}{g} = \frac{v^2 sin2\theta_2}{g}$

so after comparing above we will have

$\theta_1 = 90 - \theta$

so we have

$75 = 90 - \theta_2$

$\theta_2 = 15 degree$

Part b)

Time of flight for the first ball is given as

$T_1 = \frac{2vsin\theta}{g}$

$T_1 = \frac{2(20)sin75}{9.81}$

$T_1 = 3.94 s$

Now for other angle of projection time is given as

$T_2 = \frac{2(20)sin15}{9.81}$

$T_2 = 1.05 s$

So here the time lag between two is given as

$\Delta t = T_1 - T_2$

$\Delta t = 3.94 - 1.05$

$\Delta t = 2.88 s$

5 0

3 years ago

A Carnot air conditioner takes energy from the thermal energy of a room at 63°F and transfers it as heat to the outdoors, which

vodomira [7]

Answer:

For the Carnot air conditioner working as a heat pump between 63 and 100°F , It would transfer 3.125 Joules of heat for each Joule of electric energy supplied.

Explanation:

The process described corresponds to a Carnot Heat Pump. A heat pump is a devices that moves heat from a low temperature source to a relative high temperature destination. To accomplish this it requires to supply external work.

For any heat pump, the coefficient of performance is a relationship between the heat that is moving to the work that is required to spend doing it.

For a Carnot Heat pump, its coefficient of performance is defined as:

$COP_{HP}=\frac{T_H}{T_H-T_L}$ Where:

T is the temperature of each heat deposit.

The subscript H refers to the high temperature sink(in this case the outdoors at 100°F)

The subscript L refers to the low temperature source (the room at 63°F)

Then, for this Carnot heat pump:

$COP_{HP}=\frac{T_H}{T_H-T_L}=\frac{100°F}{100°F-63°F}=3.125$

So for each 3.125 Joules of heat to moved is is required to supply 1 Joule of work.

3 0

3 years ago

How is the motion of particles in the medium different than the motion of the wave

Ostrovityanka [42]

Answer:

The particles in a medium only vibrate about their equilibrium positions while the waves that they mediate travel through them, transferring vibration to more distant particles in the medium.

In transverse waves, like the waves on a string, the particles of the medium vibrate perpendicular to the direction of the waves. And in longitudinal waves, like sound waves, the particles vibrate in the direction of the wave's travel. What is important to stress about waves is that they do not transfer matter from one place to another, but only energy. The effect is analogous to that observed in a Newton's cradle: the ball manages to transfer energy to the other end without actually moving there.

5 0

3 years ago