Kiley went 5.7 km/h north and then went 5.8 km/h west. from start to finish, she went 8.1 km/h northwest.

which best describes her numbers?
5.7 km/h north and 5.8 km/h west are instantaneous speeds, while 8.1 km/h northwest is the average speed.
5.7 km/h north and 5.8 km/h west are average speeds, while 8.1 km/h northwest is the instantaneous speed.
5.7 km/h north and 5.8 km/h west are average velocities, while 8.1 km/h northwest is the instantaneous velocity.
5.7 km/h north and 5.8 km/h west are instantaneous velocities,

5.7 km/h north and 5.8 km/h west are instantaneous velocities, 8.1 km/h northwest is the average velocity.

Velocity is a vector quantity while speed is a scalar quantity. A vector quantity has both magnitude and direction. The direction of the vector must be taken into account in vector calculations.

We can see that at the two instants mentioned, the instantaneous velocities of the body were 5.7 km/h north and then went 5.8 km/h west. The average velocity must be obtained bearing in mind the direction of the two velocities hence 8.1 km/h northwest is the average velocity obtained from Pythagoras theorem as follows;

Vav= √(5.7)^2 + (5.8)^2 =  8.1 km/h

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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.