A200-m-wide river flows due east at a uniform speed of 2.0 m/s. a boat with a speed of 8.0 m/s relative to the water leaves the south bank pointed in a direction 30° west of north. what are the (a) magnitude and (b) direction of the boat’s velocity relative to the ground? (c) how long does the boat take to cross the river?

Explanation:

Given

Width of river=200 m

Speed of river=2 m/s

Speed of Boat relative to river=8 m/s

Boat leaves the bank west of north

Therefore velocity of boat w.r.t ground

Magnitude of boat speed

For direction

w.r.t to west

to cross the river its north component will help so

time taken

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.