Answer:
Newton's First Law of Motion.
Explanation:
Newton's first law of motion states that an object continues to stay in its state of rest, or of uniform motion, until acted upon by an external force.
So in the case of the golf ball here, the ball stays in its state of rest, on the tee, until the golf club hits it, i.e. , applies an external force on it.
Hence we can say that Newton's First Law of Motion is the principle which is most suitable for explaining this phenomenon.
Answer:
At an angle of 
Explanation:
Assume the river flows from East to West so for the swimmer to cross across it, assume he crosses it from West to East.
The resultant speed will be given by

Answer:
Use of telemetry and radar astronomy
Explanation:
An astronomical Unit (AU) is a unit of measuring distances in outer space, which is based on the approximate distance between the earth and the Sun.
After several years of trying to approximate the distance between the Sun and the Earth using several methods based on geometry and some other calculations, advancements in technology made available the presence of special motoring equipment, which can be placed in outer space to remotely monitor and measure the position of the sun.
The use of direct radar measurements to the sun (radar astronomy) have also made the determination of the AU more accurate.
A standard radar pulse of known speed is sent to the Sun, and the time with which it takes to return is measured, once this is recorded, the distance between the Earth and the Sun can be calculated using
distance = speed X time.
However, most of these means have to be corrected for parallax errors
Boyles law
Pressure and volume are inversely proportional as the new variable changes from the known.
Double the pressure equals 1/2 of original volume, assuming temperature remains the same.
So 40.0 mL is the new volume as it is compressed.