A. Upstream refers to the motion of the swimmer where he is against the current. The resultant speed of the swimmer is equal to the difference of the velocity or speed in still water and that of the river. The time it requires to cover the distance is calculated through the equation,
t = d / s
where t is time, d is distance, and s is speed. Substituting the known values,
t = 1000 m / (1.2 m/s - 0.5 m/s) = 1,428.57 seconds
(b) The time it requires for the swimmer to swim in still water,
t = 1000 m / (1.2 m/s) = 833.33 seconds
(c) Intuitively, it takes longer to cover the distance when there is current because the current will serve as resistance to the motion of the swimmer, partially moving it backwards instead of forward.
The answer is, "an unbalance force has acted on the vehicle". The vehicle will not change its states, unless otherwise there is a force acted upon on the object, that compel it to move in its original position, or to cause to change its direction of motion. This unbalance force cause the vehicle to move in the direction of the applied force.
1850 to 1900 because the slope would be 105. It says what is the greatest fall, so the upward slope of 120 wouldn't count.
An object travels in a straight line, then comes to rest
Answer: Air molecule move faster
Pressure, temperature, and volume is related to each other. If you compare sea level and 100m below sea level, 100m below sea level will have more pressure. Pressure is a force caused by molecule impact, so increased pressure means faster molecule speed. More pressure can be translated into less volume which means the air volume in the lung is decreased(with same molecule count).