When Neils Bohr shook hand with Werner Heisenberg, what kind of force they exerted?
1. Gravitational
2. Electromagnetic
3. Nuclear
4. Weak

Let E, G and N represent the magnitudes of electromagnetic, gravitational and nuclear forces between two electrons at a given separation. Then

1. N > E > G

2. E > N > G

3. G > N > E

4. E > G > N

The sum of all electromagnetic forces between different particles of a system of charged particles is zero

1. only if all the particles are positively charged

2. only if all the particles are negatively charged

3. only if half the particles are positively charged am half are negatively charged

4. irrespective of the signs of the charges

A proton exerts a force on a proton which is

(a) gravitational

(b) electromagnetic

(c) nuclear

(d) weak

Choose the correct option:

1. (a), (b) and (c)

2. (b), (c) and (d)

3. (a) and (b)

4. (b) and (c)

Mark the correct statements :

(a) The nuclear force between two protons is always greater than the electromagnetic force between them

(b) The electromagnetic force between two protons is always greater than the gravitational force between them

(c) The gravitational force between two protons may be greater than the nuclear force between them

(d) Electromagnetic force between two protons may be greater than the nuclear force acting between them

Choose the correct option:

1. (a), (b) and (c)

2. (b), (c) and (d)

3. (a), (b) and (d)

4. All of these

If all matter were made of electrically neutral particles such as neutrons,

(a) there would be no force of friction

(b) there would be no tension in the string

(c) it would not be possible to sit on a chair

(d) the earth could not move around the sun

Choose the correct option:

1. (a), (b) and (c)

2. (a), (c) and (d)

3. (b), (c) and (d)

4. All of these

A car accelerates on a horizontal road due to the force exerted by

1. the engine of the car

2. the driver of the car

3. the earth

4. the road

In an imaginary atmosphere, the air exerts a small force F on any particle in the direction of the particle’s motion. A particle of mass m projected upward takes a time t₁ in reaching the maximum height and t₂ in the return journey to the original point. Then

1. t₁ < t₂

2. t₁ > t₂ 

3. t₁ = t₂

4. the relation between t₁ and t₂ depends on the mass of the particle

A person standing on the floor of an elevator drops a coin. The coin reaches the floor of the elevator in a time \(t_1\) if the elevator is stationary and in time \(t_2\) if it is moving uniformly. Then:

A free ²³⁸U nucleus kept in a train emits an alpha particle. When the train is stationary, a nucleus decays and a passenger measures that the separation between the alpha particle and the recoiling nucleus becomes x at time t after the decay. If the decay takes place while the train is moving at a uniform velocity v, the distance between the alpha particle and the recoiling nucleus at a time t after the decay as measured by the passenger is

1. x + v t

2. x – v t

3. x

4. depends on the direction of the train