Answer:
Explanation:
Small grains are negatively charged by the wind while big grains is positively charged and remains at the ground . This process creates an electric field due to the presence of oppositely charged particles.
When ever electric field exists it is directed from a positive charge to a negative charge so the here electric field is towards an upwards direction.
Answer:
A protractor to measure the angle of the inclined plane with the horizontal
Explanation:
The student needs to lift the free end of the adjustable inclined plane until the object barely starts sliding, and measure the angle at which such happens. At that point, the force of friction equals the component of the weight in the direction of the incline. That is:

and 
Then

and therefore, the coefficient of static friction is fully determined just by calculating the tangent of the angle that the incline forms with the horizontal.
Then the only extra instrument needed is a protractor to measure the angle.
1. F
This phenomenon is in accordance with Newton's Third Law of Motion, which states that when a body exerts a force on a second body, the second body exerts a force of equal magnitude in the opposite direction on the first body. The masses of the bodies are irrelevant in this case.
Answer:
Measuring tape
Explanation:
Since we are interested in finding the distance flown by the plane, we would use an instrument measuring length. Since distance flown by the plane is quite significant, a measuring tape is used