The intensity of a sound wave is defined as the amount of energy passing through a unit area of the wave front in unit of time.
The answer is false because there are single celled organisms.
Answer:
speed of plane in still air = 1060 km/h
speed of wind = 170 km/h
Explanation:
Let teh speed of plane in still air is vp and the speed of air is va.
Irt travels 2670 km in 3 hours against the wind
So,
vp - va = 2670 / 3 = 890 km/h ..... (1)
It travels 11070 km in 9 hours along the wind.
vp + va = 11070 / 9 = 1230 km/h .... (2)
Adding both the equations
2 vp = 2120
vp = 1060 km/h
and va = 1230 - vp = 1230 - 1060 = 170 km/h
The frictional force is 39.4 N
Explanation:
We can solve this problem by applying Newton's 2nd law of motion: in fact, the net force acting on the block is equal to the product between its mass and its acceleration. So we can write

where
is the net force
m is the mass
a is the acceleration
Here we know that the box is moving with constant velocity, so its acceleration is zero:

This means that the net force is also zero:

The net force on the block is given by the applied force, forward, and the frictional force, backward:

where
is the applied force
is the frictional force
Therefore, solving for
,

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