how to explain these two explicitly?

Question

1 why does a child in a wagon seems to fall backward when you give the wagon a sharp pull forward?
2 if you walk along a log floating on a lake, why does the log move in the opposite direction?

Answer 1

1 why does a child in a wagon seems to fall backward when you give the wagon a sharp pull forward?
The body of the child is trying to resist the acceleration forward.
An object at rest will remain at rest and an object will continue in motion at constant speed in a straight line in the absence of a resultant force.

2.if you walk along a log floating on a lake, why does the log move in the opposite direction?
Newton's Third law.
An action and reaction are always equal in type and magnitude but oppositely directed on two different bodies.

Answer 2

When the wagon moves suddenly forward, the boy who is at rest tends to fall backward because of the inertia and similarly when a sudden brake is applied to the wagon, the body will move forward (that is why we need safety belts and safety inflatable bags in cars).

If we walk along a floating log or a plank, the momentum has to be compensated by the log or plank moving backwards (newton's third law-action and reaction are equal and opposite).

Answer 3

Both examples represent the same aspect ad both have the same answer. Inertia, friction and the application of force. In the first example you have two bodies in a state of where both bodies have the same speed and are therefore motionless in relation to each other. You then apply a force only to one of them .If you apply the force to the wagon the wagon will be moving faster than the child. The opposite will happen if you apply the force to the child. The child will be moving faster than the wagon and will tend to go forward. (This is what happens in you second example(both are moving at the same speed but here the force is applied by the human running forward ie faster than the log. ) Newtons law and all that.

Answer 4

Because the wagon is "pulling" the child's bottom, while his/her top (chest/head area) is not moving, yet. When the base of an object is taken out from under the object's CENTER OF GRAVITY, it will fall.

assume the person is facing to the LEFT, meaning you are looking to the side of the log. The person walks forward, and the log rolls in a clockwise direction, just like a wheel on a car driving to the right.

Answer 5

1 an object at rest remains at rest unless acted upon by an outside force...his butt on the wagon moves, his torsoe wants to stay in the same place...inertia

2 your adding an outside force to the log, your body wishes to remain in place in space do to the same effect above, your legs push the log behind you....the log has mass to so the effect is mutual, you also move forward as the log moves back you mass and the logs mass determine which moves more

Answer 6

gravity.