5k views

### How can a car's engine move the car?

Newton's First Law of Motion states that an object at rest or uniform motion tends to stay in that state of motion unless an unbalanced, external force acts on it. Say if I were in a car and I push ...
2k views

### Newton's Third Law of Motion

I want to start off by saying that I've looked around for other explanations, but I've not really found any satisfying ones. My question is basically the whole "Why can anything move at all?" question,...
8k views

### What force enables us to walk?

When we walk, we apply a force $F$ on the earth at an angle $\theta$ . Thus, by Newton's third law, $$F_{\text{me, earth}}=-F_{\text{earth,me}}$$ Therefore, the earth exerts a reaction force on us, ...
3k views

### Work done by the piston versus work done by the surrounding

Suppose a massless, frictionless piston assembly initially has a higher pressure than the external (atmospheric) pressure, and it is pinned so that the piston does not move. Once the pin is removed, ...
1k views

### How can I actually push heavier objects?

I've been thinking about Newton's third law lately because I couldn't understand a few things and I think I actually answered my own question. Could someone confirm if my reasoning is right or show me ...
2k views

### Does Newton's 3rd law of motion apply when a person is standing still on a ground?

When a person is standing still, the action of the Earth on their body is a gravitational force. What is the reaction force? Is it the person's weight acting on the Earth?
2k views

### How muscle force work? [closed]

If muscle works with force on joint and joint works with exact force on muscle(newton III law) how can muscle drag much heavier weight than itself?
1k views

### Force exerted by piston in a gas container and work done

If there is container with a moveable piston. If heat is supplied to it the gas in container expands right raising the volume. The gas expands raises the piston against gravity (the gas does positive ...
205 views

### How does the Earth bring down a falling object's velocity to zero on contact?

How does the earth bring down a falling object's velocity to zero on contact? If the normal force on an object from a horizontal surface is equal to the weight of the object, the object could never ...
697 views

### Action and Reaction - Time lag

Is there a time lag between action and reaction ? If there isn't such a time lag, the reaction force must cancel the applying force although they act on different bodies. My second question is that, ...
232 views

### Force (Newton's third law of motion) [duplicate]

When we apply a force, there's always a reaction force too. Why do forces always come in pairs?
100 views

### Can force be applied without accelerating?

When I push against a wall, I am applying force on the wall and the wall applies an equal force against mine therefore the wall doesn't move and neither does my hand. But isn't acceleration required ...
741 views

### When I pull a rope attached to a block, does the rope OR the block pull me back? If so, with what force?

I am having a hard time understanding the tension force, especially when thinking about it at a molecular level. Suppose I have a rope attached to a block which is sitting on frictionless surface. ...
$R$ = Normal reaction force exerted on the particle by the ground $Fr$ = Frictional contact force between the particle and the ground All forces are measured in Newtons ($N$) Using the angles we ...