An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is, because
the two magnetic forces are equal and opposite, so they produce no net effect
the magnetic forces do not work on each particle
the magnetic forces do equal and opposite (but nonzero) work on each particle
the magnetic forces are necessarily negligible
Get Answer
When electron and proton are moving under influence of their mutual forces, then according to the flemings left hand rule, the direction of force acting on a charge particle is perpendicular to the direction of motion.
In magnetic field, work-done
A proton is kept at rest. A positively charged particle is released from rest at a distance in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. In the same time , the work done on the two moving charged particles is
same as the same force law is involved in the two experiments
less for the case of a positron, as the positron moves away more rapidly and the force on it weakens
more for the case of a positron, as the positron moves away a larger distance
same as the work done by charged particle on the stationary proton
Forces between two protons is same as that of between proton and a positron.
As positron is much lighter than proton, it moves away through much larger distance compared to proton.
Work done Force Distance
As forces are same in case of proton and positron but distance moved by positron is larger, hence, work done on positron will be more than proton.
A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is
constant and equal to in magnitude
constant and greater than in magnitude
variable but always greater than
at first greater than and later becomes equal to
When the man squatting on the ground he is tilted somewhat, hence he also has to apply frictional force besides his weight.
(reactional force) friction force i.e.,
When the man does not squat and gets straight up in that case friction
(Reactional force)
Hence, the reaction force is larger when squatting and become equal to when no squatting.
A bicyclist comes to a skidding stop in . During this process, the force on the bicycle due to the road is and is directly opposed to the motion. The work done by the cycle on the road is
zero
According to the question, work done by the frictional force on the cycle is :
As the road is not moving, hence work done by the cycle on the road is zero.
A body is falling freely under the action of gravity alone in vaccum. Which of the following quantities remain constant during the fall?
Kinetic energy
Potential energy
Total mechanical energy
Total linear momentum
As the body is falling freely under gravity and no external force act on body in vaccum so law of conservation, the potential energy decreases and kinetic energy increases because total mechanical energy (
of the body and earth system will be remain constant.
During inelastic collision between two bodies, which of the following quantities always remain conserved?
Total kinetic energy
Speed of each body
According to the question, consider the two bodies as system, the total external force on the system will be zero. Hence, in an inelastic collision KE does not conserved but total linear momentum of the system remain conserved.
Both the stones reach the bottom at the same time but not with the same speed
Both the stones reach the bottom with the same speed and stone I reaches the bottom earlier than stone II
Both the stones reach the bottom with the same speed and stone II reaches the bottom earlier than stone I
Both the stones reach the bottom at different times and with different speeds
As the (inclined surface) are frictionless, hence, mechanical energy will be conserved. As both the tracks having common height, (and no external force acts on system).
of stone at top at bottom of .
From conservation of mechanical energy,
similarly
Hence, speed is same for both stones.
For stone I, acceleration along inclined plane
Similarly, for stone II
Thus, hence .
is greater than and both length for track II is also less hence, stone II reaches earlier than stone I.
The potential energy function for a particle executing linear SHM is given by where
is the force constant of the oscillator (Fig.). For , the graph of versus is shown in the figure. A particle of total energy turns back when it reaches . If and indicate the and , respectively of the particle at , then which of the following is correct?
Total Mechanical energy is at any instant. When particle is at .i.e., at extreme position, partical returns back and its velocity become zero for an instant. Hence, at , K.E. .
From Eq. (i),
but at mean position at origin .
Two identical ball bearings in contact with each other and resting on a frictionless table are hit headon by another ball bearing of the
same mass moving initially with a speed as shown in figure.
If the collision is elastic, which of the following (figure) is a possible result after collision?
If two bodies of equal masses collides elastically, their velocities are interchanged.
When ball 1 collides with ball-2, then velocity of ball-1, becomes zero and velocity of ball-2, becomes , i.e., similarly then its own all momentum is .
So,
Now ball 2 collides to ball 3 and its transfer it's momentum is to ball 3 and itself comes in rest.
So, ball 1 and ball 2, become in rest and ball 3 move with velocity in forward direction.
A body of mass travels in a straight line with velocity where . The work done by the net force during its displacement from to is
As we know that,
W.D.
As given that, ,
We also know that Acceleration,
Now, force
From (i), work done
General Knowledge
Academics Question Bank
PHYSICS
CHEMISTRY
BIOLOGY
MATHEMATICS
THE WORLD AROUND US
HISTORY
GEOGRAPHY
CIVICS
ECONOMICS
Physics
How - Why - What
NCERT Books (Class 1-12)
Learn At Your Own Pace... Because, Everyone's Pace of Learning is Different...
A unit of Innovexcel Edu Solution LLP.
SWIFT, RELIABLE & CONVENIENT..
Social Media
Corporate Office : Bharat Impact Building, C-26, Sector - 59, Noida, Uttar Pradesh - 201301, India
Excel With Tutors : A Perfect Tutoring Platform & Repository of Learning Materials. Matches the Best Tutor as Per Your Requirement.
© 2025 | ©Innovexcel Edu Solution LLP. All Rights Reserved.
Technology Partner: Indev Consultancy Pvt Ltd