From rest you suddenly stand up and start walking. But according to Newton's first law there has to be a force for change of state. What force made you move?
From rest you suddenly stand up and start walking. But according to Newton's first law there has to be a force for change of state. What force made you move?
The correct option is D Friction force by ground
Let's go through the options
(a) Muscular force:- you apply Muscular force on other objects and not on yourself else I would start moving by just hitting myself.
(b) Chemical force:- Well this option is similar to the previous one. You eat food, then you digest it and get chemical energy which helps you in doing muscular work.
(c) Normal force:- As the name suggests normal force is normal to the contact surface. Your feet are in contact with ground. So normal is in vertical direction. But the motion is horizontal. And I know vertical and horizontal are independent so, vertical force can't create horizontal motion.
(d) Friction force:- This opposes relative motion.
When you walk forward, you are trying to slip your foot backward. Try doing it.
The ground is stationary but relative to it you are moving your foot backward hence friction would be in forward direction and on you.
Finally I have an external force on my body that too in the direction of motion.
Phew - - - - - - - - - -
I can clearly conclude that this is the force responsible for my forward motion.
Friction force by ground
Let's go through the options
(a) Muscular force:- you apply Muscular force on other objects and not on yourself else I would start moving by just hitting myself.
(b) Chemical force:- Well this option is similar to the previous one. You eat food, then you digest it and get chemical energy which helps you in doing muscular work.
(c) Normal force:- As the name suggests normal force is normal to the contact surface. Your feet are in contact with ground. So normal is in vertical direction. But the motion is horizontal. And I know vertical and horizontal are independent so, vertical force can't create horizontal motion.
(d) Friction force:- This opposes relative motion.
When you walk forward, you are trying to slip your foot backward. Try doing it.
The ground is stationary but relative to it you are moving your foot backward hence friction would be in forward direction and on you.
Finally I have an external force on my body that too in the direction of motion.
Phew - - - - - - - - - -
I can clearly conclude that this is the force responsible for my forward motion.
