Physics Chapter 10 Flashcards
Define electric potential at a point in an electric field. [3]
The work done per unit charge [1] to bring a positive test / point / small charge [1] from infinity to that point [1]
State Coulomb’s law. [2]
The force between two point charges is directly proportional to (the product of) their magnitudes [1] and inversely proportional to the square of their separation [1]
Define electric field strength. [2]
The force per unit charge [1]
exerted on a positive test / point / small charge in the electric field [1]
State what is meant by gravitational field strength. [1]
The force per unit mass exerted on a point / small / test mass
Outline why the gravitational potential is negative. [2]
It is because the gravitational potential is taken as zero at infinity [1] and a positive work is needed to be done to move a mass to infinity. [1]
Explain what is meant by the gravitational potential at the surface of a planet. [2]
The (negative of) work done (by an external force) per unit mass [1] to move a small mass from infinity to the surface of a planet [1]
Explain why astronauts inside a spaceship orbiting the Earth would feel “weightless”, even though there is a force acting on them. [3]
It is because the astronauts and the spaceship have the same acceleration. [1]
The acceleration points towards the centre of the Earth. [1]
So there is no reaction between the astronauts and the spaceship. [1]
Outline what is meant by the escape speed of a rocket. [1]
The minimum launching speed of a rocket to move it from the surface of a planet to infinity
Define gravitational potential energy of a mass at a point. [1]
The work done (by an external force) to move a mass from infinity to a point.
