Explanation:

Statement I is incorrect. This is due to Newton’s Law of Gravitation. The astronaut will experience gravitational force from the Earth that acts as the centripetal force.

Since the centripetal force is the gravitational force, then the centripetal acceleration is equal to the gravitational field strength at that point. Therefore both the astronaut and the space station experience the same acceleration. Then statements II and III are correct.

Explanation:
Conventional current will flow anticlockwise due to the orientation of the cell. To determine the force experienced by a current carrying conductor in a magnetic field, use (any appropriate hand-rule convention or) Flemming's left hand rule which states that if we arrange our thumb, forefinger and middle finger of the left-hand perpendicular to each other, then the thumb points towards the direction of the force experienced by the conductor, the forefinger points towards the direction of the magnetic field and the middle finger points towards the direction of the electric current.

Explanation:
According to Newton's third law, the two objects exert equal and opposite forces on each other.

The equation

• Fg=GMm/r

also shows that the forces on the planets are equal in magnitude.

Explanation:

The hydrogen nucleus is a proton, so it has positive charge.

The electric field lines are pointed upwards, meaning the higher potential is below the nucleus, or meaning that the force on the nucleus is upward.

The question asks for the largest work done, therefore we are looking for the largest displacement parallel and in the opposite direction the field lines. This is shown in D

Explanation:
Summing the four electric field vectors from the individual point charges, the fields from the charge at the top left and the bottom right will cancel out. The fields from the bottom left and top right will add together to give a net field in the direction of the charge in the top right.

Explanation:
The gravitational field strength varies inversely with the square of the distance from the center of the planet ($R$) to a given point.

g=GM/(R)^2

This means the variation of the gravitational field strength with $R$ is an inverse square law. Note, however, that the question asks for the relationship from the distance from the surface of the planet, therefore the graph starts at a finite value of field strength at the surface ($r=0$), then follows the shape of an inverse square curve.

Explanation:
The electric field strength direction is the same as the direction of the electric force.

The electric field will be directed out of the rod in all directions, as it contains uniformly distributed positive charges.

Getting the vector sum for the electric field, due to symmetry the total electric field strength will be directed out of the rod with an angle away from the midpoint of the rod as shown

Also we can think of B as the only correct solution, because it’s a positively charged rod, so the direction must be out of the rod.

Explanation:
The force acting on the electron is downward at entry and perpendicular to the velocity, and the electron has negative charge. Using conventional methods (right-hand/left-hand) the magnetic field vector points into the plane of the paper

Explanation:

The electric field at X due to -Q points toward -Q. The field at X due to +Q points away from +Q, with the same magnitude at X as the field from -Q. Adding the electric field vectors gives a vector pointing to the left.

Explanation:
The direction of the current is perpendicular to the magnetic field in both regions and the magnitude of the field is unchanged. So the magnitude of the force is $F$.

Using Fleming's left hand rule, direction of the force is

Explanation:

Because the electric field lines point toward the charge $q$, this charge must be negative, meaning that statement I is false.

The relatively greater number of field lines around charge $q$ means that this charge magnitude is greater than the charge +Q, indicating that statement II is also untrue.

Electric field line density is proportional to electric field strength. Because the field line density near $q$ is greater than that near $+Q$, statement III is correct.

Therefore the correct answer is option C.

Explanation:
Because the electric field is only in the vertical direction, it does not affect the electrons' horizontal speed.

As described by E=F/q in the data booklet, the electrons do experience a vertical force which causes them to accelerate vertically.

Therefore when they enter the electric field, the horizontal speed of the electrons remains the same while their vertical speed increases.

Explanation:
Choice A is incorrect as it equates the gravitational field strength with the gravitational force and these two are two different physical quantities.

Choice B is the correct answer, since the gravitational field strength equals to force per unit mass; g=F/m.

Choice C is incorrect, because the gravitational field strength is inversely proportional to the square of the distance between the center of mass of the planet and that point; g=GM/r2

Choice D is incorrect, because the gravitational field strength depends on the mass of the planet; g=GM/r2.

Explanation:
The alpha, beta and gamma radiation have different penetrating powers, where alpha is the one with the least penetrating power and won’t pass through the paper sheet, while gamma and beta radiations will pass through the paper sheet.

When entering the magnetic field, gamma radiation will continue in its path without deflection because they have no charge. On the other hand, beta particles have negative charges, so they will be affected by a magnetic force that causes deflection in their path.

To determine the direction of the magnetic force, the right hand rule is used keeping in mind that the velocity direction in the right hand rule is that of a positive charge. So we have the direction of velocity is to the left, the magnetic field is into page, thus the magnetic force will be directed downwards.

*Any other hand-rule convention can also be used.