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Answer:
false statement : b ) For the motion of a cart on an incline plane having a coefficient of kinetic friction of 0.5, the magnitude of the change in kinetic energy equals the magnitude of the change in gravitational potential energy
Explanation:
mechanical energy = potential energy + kinetic energy = constant
differentiating both side
Δ potential energy + Δ kinetic energy = 0
Δ potential energy = - Δ kinetic energy
first statement is true.
Friction is a non conservative force so inter-conversion of potential and kinetic energy is not possible in that case. In case of second option, the correct relation is as follows
change in gravitational potential energy = change in kinetic energy + work done against friction .
So given 2 nd option is incorrect.
In case of no change in gravitational energy , work done is equal to
change in kinetic energy.
Answer:
The answer is the option a.
Explanation:
We know that magnetic force (Fm) is defined as
Fm = q (v x B)
Where q is a the value of the charge, v is the velocity of the charge and B is the value of the magnetic field.
"v x B" is defined as the cross product between the vectors velocity and magnetic field, and if the angle between them is thetha < 180°, then, the cross product is
v x B = vBsin (thetha)
So,
Fm = qvBsin (thetha)
And, in case in which v and B are parallel vectors, thetha is zero, and,
sin (thetha)=sin (0) = 0
So, Fm=0
