Which of the following systems may be adequately described by classical physics?

a.	motion of a cricket ball
b.	motion of a dust particle
c.	a hydrogen atom
d.	a neutron changing to a proton

Choose the correct option:

1.	(a) and (b)
2.	(b) and (c)
3.	(c) and (d)
4.	(a) and (d)

The two ends of a spring are displaced along the length of the spring. All displacements have equal magnitudes. In which case or cases the tension or compression in the spring will have a maximum magnitude?

Choose the correct option:

Action and reaction

(a) act on two different objects
(b) have equal magnitude
(c) have opposite directions
(d) have resultant zero

Choose the correct option:

1. (a) and (b)
2. (b) and (c)
3. (a), (b) and (c)
4. All of these

A body of weight \(\mathrm{w}_{1}\) is suspended from the ceiling of a room through a chain of weight \(\mathrm{w}_{2}.\)The ceiling pulls the chain by a force:

When a horse pulls a cart, the force that helps the horse to move forward is the force exerted by:

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

A block of mass \(10\) kg is suspended through two light spring balances as shown in the figure:

A block of mass m is placed on a smooth inclined plane of inclination θ with the horizontal. The force exerted by the plane on the block has a magnitude

1. mg

2. mg/cosθ

3. mg cosθ

4. mg tanθ

A block of mass m is placed on a smooth wedge of inclination θ. The whole system is accelerated horizontally so that the block does not slip on the wedge. The force exerted by the wedge on the block has a magnitude:

1. mg

2. mg/cosθ

3. mg cosθ

4. mg tanθ

Neglect the effect of rotation of the earth. Suppose the earth suddenly stops attracting objects placed near its surface. A person standing on the surface of the earth will: