Tag: physics

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Questions Related to physics

Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

Which of the following is the weakest force?

  1. Nuclear force

  2. Gravitational force

  3. Electromagnetic force

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is B.

Gravity is a very, very weak force. In a hydrogen molecule it pulls the two protons together with a force about 36 powers of ten weaker than the electric force between them.
Therefore, on small scales (within an atom/molecule), the other forces are much stronger, but on larger scales, it seems that gravity is a far stronger force; e.g. planets are held to the sun by gravity. 
Hence, among the given options, gravitational force is the weakest.

Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

There are circumstances in which two objects exert forces on one another even though they are not touching. Such forces are called (Mark the most appropriate answer)

  1. non-contact forces

  2. contact forces

  3. electric forces

  4. attractive forces
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A non-contact force is a force applied to an object by another body that is not in direct contact with it. The most familiar example of a non-contact force is weight.

Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

It is easier to drive a screw rather than a nail of the same size into a wall because:

  1. The nail moves a larger distance for the same force applied

  2. The screw moves a larger distance for the same force applied

  3. The direction of force applied in the screw is perpendicular to its movement

  4. The screw acts as a wedge
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In screws the direction of force applied is perpendicular to the wall and due to its cuts present their is a force applied tangential to the wall which helps in easy movement of the screw.

Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

Which of the following is a non contact force?

  1. muscular

  2. electrostatic attraction

  3. elastic spring force

  4. friction force
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Coulomb electrostatic force of attraction acts between the two bodies which are separated by a finite distance, hence it is non contact force since the two bodies need not to be in contact with each other whereas the rest of the forces are contact forces.

Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

Let E,G and N represents the magnitude of electromagnetic, gravitational and nuclear forces between protons and electrons at a given separation (1 fermi meter). Then

  1. N < E < G

  2. E > N > G

  3. G > N > E

  4. N > E > G
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$r=1fermimeter$ which is same for all.
$F _e=\frac{k _eq _1q _2}{r^2}  ;F _g=\frac{Gm _1m _2}{r^2}$ ; 
$F _N=\frac{\alpha}{r^2}$
where$k _e=8.988\times10^9 N^2m^2c^{2} $;
$q _1=-1.6\times10^{-19}c$; 
$q _2=1.6\times10^{19}$;
$G=6.67\times10^{-11}m^3kg^{-1}s^2$;
$m _1=9.1\times10^{-31}kg$; 
$m _2=1.67\times10^{-27}kg$;
$\alpha=2.3103\times10^{-28}$
$F _e=2.307\times10^{-28}$  ; ${F _g}=1.868 \times10^{-64}$ ;
$F _N=2.3103 \times10^{-28}$
hence,$F _N>F _e>F _g$


Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

State whether the given statement is true or false :
Gravity and friction are both contact forces. 

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is B.

The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. All objects upon earth experience a force of gravity that is directed "downward" towards the center of the earth. 
The friction force is the force exerted by a surface as an object moves across it or makes an effort to move across it. There are three types of frictional force - sliding and static friction. Though it is not always the case, the friction force often opposes the motion of an object. 
Hence, gravity is a non-contact force and friction is a contact force.

Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

Gravitational force acts

  1. only between the sun and the planets moving around it.

  2. only between the earth and the bodies on it.

  3. between all bodies in the universe.

  4. only between the Sun and the earth.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Answer is C.

The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. Gravitational force exists between all the bodies having mass in the universe.