**Answer:**

1.718 N , attractive

**Explanation:**

r = 0.66 m, n = 5.7 x 10^13

q1 = 5.7 x 10^13 x 1.6 x 10^-19 = 9.12 x 10^-6 C

q2 = - 5.7 x 10^13 x 1.6 x 10^-19 = - 9.12 x 10^-6 C

F = K q1 q2 / r^2

F = 9 x 10^9 x 9.12 x 10^-6 x 9.12 x 10^-6 / (0.66)^2

F = 1.718 N

As both the charges are opposite in nature, so the force between them is attractive.

**Answer:**

**43.88 meters per second**

**Explanation:**

The computation of the speed is shown below:

As we know that

where,

Distance is 395,000 meters

Time is 9,000 seconds

Now placing these values to the formula

So, the speed is

= **43.88 meters per second**

As speed shows the relation between the distance and time and the same is to be considered i.e by applying the formula

**Answer:**

4.9 m/s²

**Explanation:**

Draw a free body diagram. There are two forces on the object:

Weight force mg pulling straight down,

and normal force N pushing perpendicular to the plane.

Sum the forces in the parallel direction.

∑F = ma

mg sin θ = ma

a = g sin θ

a = (9.8 m/s²) (sin 30°)

a = 4.9 m/s²

By Increasing the amplitude, Increasing the frequency and Increasing the tension on the spring

Answer:

Rhizobium.

Explanation:

The roots of most of these plants have nitrogen-fixing bacteria known as rhizobium. It helps to change nitrogen which is present in the air into the nitrates which are plants, and that is need to synthesize proteins.

Rhizobium bacteria occupy the root hairs which are present on the plants, they help the plant to grow and keep up with other plants. When the one plant dies, the fixed nitrogen which is present in it will release, and making it available for other plants, and this process helps to fertilize the soil in the environment.