Answer:
26000 years
Explanation:
Precession describes the angular motion of the Earth's body. Since the attitude of telescopes relative to the Earth's body can be controlled with high accuracy, and telescopes can measure the direction of incoming light also with high accuracy, the motion of Earth is under permanent high precision monitoring. Thus the basic numerical descriptor of precission, an angular rate of 5029.0966 seconds of arc per Julian century, traditionally denoted p (for precession) is a measured value from observed coordinate changes of thousands of stars over, say, two centuries. The understanding of this value in terms of forces acting on an oblate Earth from the Moon is well understood so that an extrapolation back and forth over a few full cycles contains little uncertainties. Of course, you can find details on the coordinate transformations mentioned above (the direct observational effect of precession) on the net. I was surprised to see that the Wikipedia article on precession covers the astronomical aspect very poorly. You thus better look for other sources.
Answer:
Approximately 
.
Assumption: air resistance on the rocket is negligible. Take 
.
Explanation:
By Newton's Second Law of Motion, the acceleration of the rocket is proportional to the net force on it.
.
Note that in this case, the uppercase letter 
in the units stands for "mega-", which is the same as 
times the unit that follows. For example, 
, while 
.
Convert the mass of the rocket and the thrust of its engines to SI standard units:
- The standard unit for mass is kilograms:
. - The standard for forces (including thrust) is Newtons:
.
At launch, the velocity of the rocket would be pretty low. Hence, compared to thrust and weight, the air resistance on the rocket would be pretty negligible. The two main forces that contribute to the net force of the rocket would be:
- Thrust (which is supposed to go upwards), and
- Weight (downwards due to gravity.)
The thrust on the rocket is already known to be 
. Since the rocket is quite close to the ground, the gravitational acceleration on it should be approximately 
. Hence, the weight on the rocket would be approximately 
.
The magnitude of the net force on the rocket would be
.
Apply the formula to find the net force on the rocket. To make sure that the output (acceleration) is in SI units (meters-per-second,) make sure that the inputs (net force and mass) are also in SI units (Newtons for net force and kilograms for mass.)
.
Answer:
F= 403429 kpa
Explanation:
Pressure is the product of force and area
Mathematically,
P=F*A -------where F is force and A is area.
A= 40 *0.1 = 4mm² -----convert to m²
A= 4e⁻⁶ m²
P= 4000000 pa
F= P/A = 4000000/4e⁻⁶
F= 403428793.493 pa
F= 403429 kpa
