If a river current is 8.0 m/s, and a boat is traveling 10.0 m/s upstream, what is the boat’s speed relative to the riverbank?

The relative speed of the boat is found to be - 2 m/s or 2 m/s in opposite direction to the river current.

Explanation:

Let us, consider the direction of river as the reference of positive direction. Hence,

Speed of River = Vr = 8 m/s

Since, the boat is traveling upstream. The upstream direction means that the boat is traveling in the opposite direction of the river current. Therefore, its direction will be negative. Hence,

Speed of boat = Vb = - 10 m/s

Now, the relative speed will be the vector sum of both speeds, with relative directions:

Relative Speed = V = Vr + Vb

V = 8 m/s - 10 m/s

V = - 2 m/s

This shows that the magnitude of speed of boat is 2 m/s and its direction will be opposite to that of river current.

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.

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2