## Electric field point charges and direction of electric field.

An electric field is a physical quantity that describes the influence that electric charges have on each other. An electric field is a vector field, meaning that it has both a magnitude and a direction at each point in space.

Point charges are electric charges that are concentrated at a single point in space. The electric field created by a point charge at a point in space is given by Coulomb’s law:

E = k*q/r^2

where E is the electric field at the point, k is Coulomb’s constant, q is the charge of the point charge, and r is the distance between the point charge and the point where the electric field is being measured.

The direction of the electric field at a point in space is the direction in which a small positive test charge would be pushed or pulled if it were placed at that point. For a positive point charge, the electric field points radially outward from the charge, while for a negative point charge, the electric field points radially inward towards the charge.

The magnitude of the electric field decreases as the distance from the point charge increases. Therefore, the electric field created by a point charge becomes weaker as the distance from the charge increases. For more information see the video attached

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## Grade 11 Newton Laws QUESTION

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A tow truck is towing a car using an inelastic steel cable (of negligible mass) as shown in the diagram below. The steel cable forms an angle of 30° with the horizontal.

The two vehicles move from rest on a straight, horizontal road to the right. The mass of the car is 1100 kg and the mass of the tow truck is 4000 kg. The tow truck’s engine applies a force of 15 000 N. A constant frictional force of 1456 N is acting on the car and a constant frictional force of 4520 N is acting on the tow truck respectively.

3.1 State Newton’s Second Law of motion, in words. (2)

3.2 Draw a labeled, free-body diagram of all the forces acting on the car. (4)

3.3 Calculate the:

3.3.1 acceleration of the car. (6)

3.3.2 magnitude of the tension T in the cable. (3)

3.5 Using equations of motion, calculate the distance that the car will travel in 4s. (2)

3.6 State Newton’s First Law of motion, in words. (2)

3.7 Use Newton’s laws of motion to explain why towing can be dangerous. (2)

3.8 If the force of horizontal tension in the cable, from the car on the truck, is 1890 N, what is the horizontal force of the truck on the car? Explain with reference to the relevant scientific principles. (2) [23]

## PHYSICAL SCIENCES GRADE 11 CONTROLLED TEST TERM 4 2021

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Paper shared with the help KC Kakinda