Answer:
Instantaneous speed means speed at any instant
that means Speed is changing with time
You know speed is distance/time
So that means distance is also changing with time
So we take infinitesimal small distance per infinitesimal small time As we assume speed is constant in infinitesimal small time dt
So, we take speed = ds/dt
ds = infinitesimal small distance
dt = infinitesimal small time
As its ratio is equal to speed at any instant
Note : We are taking infinitesimal small distance
But :) we are taking infinitesimal small time also
As you know if denominator is small fraction is large So fraction always give large value
So it's not O ( this makes confuse to most of students)
So, thanks
Good question
Keep thinking like this :)
Answer: The correct answer is Image B.
Explanation: For an object to accelerate, there should be unbalanced forces present. An object will move in the direction of net force.
Balanced forces are defined as the forces acting on the same object which are equal in magnitude but act in opposite direction. The net forces are 0.
Unbalanced forces are defined as the forces acting on the same object which are unequal in magnitude. The net force is non-zero.
For the given images:
Image A: This box will accelerate easily because the net force is non-zero and is moving in right direction.
Image B: This box will not accelerate because the net force is zero as all the forces are balancing one another. Hence, the object will stay at rest.
Image C: This box will accelerate easily because the net force is non-zero and is acting in between the normal and applied force.
Image D: This box will accelerate easily because the net force is non-zero and is moving in right direction.
Hence, the correct option is Image B.
The net force does not depend on the mass.
We have 12N to the right, and 19N to the left.
The net force is (19.0-12.0)N=7.0N to the left.
