<span>when it returns to its original level after encountering air resistance, its kinetic energy is

**decreased**.

In fact, part of the energy has been dissipated due to the air resistance.

The mechanical energy of the ball as it starts the motion is:

</span>

<span>where K is the kinetic energy, and where there is no potential energy since we use the initial height of the ball as reference level.

If there is no air resistance, this total energy is conserved, therefore when the ball returns to its original height, the kinetic energy will still be 100 J. However, because of the presence of the air resistance, the total mechanical energy is not conserved, and part of the total energy of the ball has been dissipated through the air. Therefore, when the ball returns to its original level, the kinetic energy will be less than 100 J.</span>

I’m assuming we’re suppose to get some kind of graph but, Instantaneous speed is the speed that is happening right now. Like driving a car at 15k/h. The instantaneous speed of the car 15k/h. On the graph, at 5s. Wherever the line is, will tell you what the speed is.

**Answer:**

<u>**velocity of swimmer relative to ground = 3 i -5 j**</u>

**Explanation:**

- To cross a river the swimmer swims relative to river in perpendicular direction.

Velocity of river = -5 j (south)

Velocity of swimmer relative to river = 3 i(north)

So

<h2>

**Velocity of swimmer relative to ground = Velocity of swimmer relative to river + Velocity of river**</h2>

Velocity of swimmer relative to ground = 3 i -5 j

So magnitude of total velocity is = =

**Answer:**

-0.0047 rad/s²

335.103 seconds

99.18 seconds

**Explanation:**

= Final angular velocity

= Initial angular velocity = 1.5 ra/s

= Angular acceleration

= Angle of rotation = 40 rev

t = Time taken

Equation of rotational motion

**Acceleration while slowing down is -0.0047 rad/s²**

**Time taken to slow down is 335.103 seconds**

Solving the equation

**The time required for it to complete the first 20 is 99.18 seconds as 539.11>335.103**

<span>Is it true that nighttime air temperatures on a cloudy night are lower than they would be on a clear night?</span>