can u solve this question on laws of motion for me please?

Question

According to the third law of motion when we push on an object,
the object pushes back on us with an equal and opposite force.
If the object is a massive truck parked along the roadside, it
will probably not move. A student justifies this by answering
that the two opposite and equal forces cancel each other.
Comment on this logic and explain why the truck does not
move.

Answer 1

The laws of motion does not take into account the effects of gravity and friction, and are usually stated in an environment (say space) where the only force exerted on the moving object is the pusher and the object itself.

A small object, say a pencil, will move when pushed because its mass is small and the force of the push exceeds the gravitational force on the object. A truck is much bigger. Its mass far exceeds that of a pencil, thus, the force of gravity on the truck will greatly exceed the force of the human push, the truck, therefore does not move.

Answer 2

If a person pushes a massive truck, the truck pushes the person with an equal force in the opposite direction. Only a single forcr acts on each , so there is no question of cancellation of the forces.
The truck does not move because of the fact that the applied fortce is not suffient to overcome the friction between the axle and the bearings that hold the axle and also in the transmission system coupled to the axle.
On the other hand the force, equal and opposite to the applied force, that the truck exerts on the person, which is called the reaction, may be enough to push the person back and cause him to slip if the friction between his feet and the surface on which he is standing is not very large.

Answer 3

The reason for lack of motion is not cancellation of the forces, which are indeed equal and opposite, but rather static friction. The force exerted by a person is not likely to overcome the friction on either himself or the truck due to the traction of the roadside. If this happened on ice, the person would probably push himself back, because the force might overcome the friction on himself, but not the greater friction on the truck. If it happened on a truly frictionless surface, the person and the truck would move apart with equal but opposite momentums, or with velocity inversely proportional to mass. So the person would move faster than the truck.

Answer 4

first of all i must explain the exact concept of action and reaction.

cosider two objects colliding with each other, then one will put an action force on other, so according to the third law the second object will create a reaction force which will be applied on the first object. so action and reaction are not applied on the same object at all. the students explanation as "two opposite and equal forces cancel each other" is faulty. take an example below:

when we hang objects in a spring balance to measure its weight (in Newton) you get a certain value. but observe simultaneously the object is hanging and u are getting a reading in the meter. the objects weight as the action is responsible for the reading. and the tension by the balance as reaction will cause it hang inequllibrium. these 2 forces are surely equal but not acting on the same object.

now here is the answer of "why the truck doesnt move?"

this happens for static friction force, if you apply a force on the truck, the surface on which its trying to move will create a friction on the truck which'll equate your force in the opposite direction and thus equal and opposite force on the same object will cancel each other. until your force doesnt exceed the limiting friction value, the truck will not get any net momentum. the value of limiting equates "μR"
μ=coefficient of static friction
R=the truck's weight

for clearer understanding, you can get a better example. apply the same force on a toy truck. you'll see how fast it runs!!!

Answer 5

That's right when u apply a force on an object it does provide an equal and opposite reaction to the cause that forces it to change it's inertia.Now that u r pushing a truck(Action) the reaction is the friction
that acts preventing u to push forward,when it moves forward the reaction is still equal to the force exerted by u but isn't equal to the frictional force and hence it moves forward.While considering the 3rd law of motion certain things r to be considered:
1) Action and reaction must take place simultaneously.
2)Action and reaction never acts on the same body.

Answer 6

The student is correct. That force is called "friction". (There's also inertia to overcome but the effect is negligible compared to friction.) If I push on a truck with 20 lbs of force, the truck will push back with 20 lbs of force from friction. If the truck's friction was zero and I could apply a 20 lb force to it, the truck would begin to move. If I was in space, inertial effects would be the only force to overcome. If I pushed on a very massive object, we would both move, the one with the less mass much more so than the massive one. If I was attached to the space station, I could push a very, very heavy payload with little force because friction is negligible.

Answer 7

Not opposite and equal, but the greater force wins out (the truck). The truck pushes back with a force greater than is being applied to it. Thus it does not move.

Answer 8

Because even if you push on the truck it has more mass than you do and if opposite equal force cancel each other then actually the truck is winning because it has more mass. If would take more force to move it.

Answer 9

I think u have forgotten the first law of motion. Which simply is the
law of inertia. A body will not move untill a force more than what earth exerts on it is applied. Hence in the case when u push a truck u dont have that much stamina to move the truck .

Answer 10

It is not the case--- the greater force wins out here it is the truck

also the tyres of truck are under friction so it wont move and here truck is a larger force and so it wontmove so it has no relation
with newtons third law it is just an application