33 Answered Questions for the topic newtonian mechanics
Why is less force required to open a door when we apply a force at a greater distance from the hinge?
I know that the magnitude of a torque increases with the distance from the axis of rotation. What is the reason of that : how can a force exert a greater torque when the force is applied at a... more
I'm trying to understand tension. So here it goes: I'll start from the beginning. Let's assume I'm in space and can move around and apply forces. Let's say a rope is attached to a body(which is... more
Small car colliding with large truck?
A small car collides with a large truck. Why do both vehicles experience the same magnitude of force? Wouldn't the large vehicle experience less force than the small one?
Why can't charged objects exert electrostatic forces on heavier objects?
We know that, for example, amber rubbed with fur attracts bits and pieces of straw, paper, Styrofoam, etc. which are all light objects. Why don't they attract heavier objects, likewise?
Why do we take small steps while walking on ice?
> When we walk on ice we should take small steps. Small steps ensure: > > a.)larger friction. > > b.)small friction. > > c.)larger normal force. > > d.)smaller... more
Which is easier, pushing or pulling?
It is generally assumed, from a person's perspective, that pushing a cart is more easier than pulling one. But why? Is there any difference in terms of force required to achieve the same amount of... more
Why don't we consider jerk in physics classes?
When I got more into physics, I started asking myself if just like acceleration represents the growth of speed, something else could also represent the growth of acceleration itself. And it came... more
Why is a book on a table not an example of Newton's third law?
My textbook explains Newton's Third Law like this: > If an object A exterts a force on object B, then object B exerts an equal but opposite force on object A It then says: > Newton's 3rd... more
Why does Newton's third law exist even in non-inertial reference frames?
While reviewing Newton's laws of motion I came across the statement which says Newton's laws exist only in inertial reference frames except the third one. Why is it like that?
Why does an unhinged body rotate about its centre of mass?
If a force is applied to a body which does not act through its centre of mass, it rotates about its centre of mass and not any other point. Why?
Why does a car engine not do work if the wheels don't slip?
I saw this mind boggling result that if the tires don't slip then the work done by an engine to move a car is zero. Why is this true? Moreover, what does this truly mean? **Update:** Sorry about... more
When is tension constant in a rope?
Suppose we have a massless rope with pulling forces applied at each end. In which scenarios is the tension in the rope constant throughout? For example if there is a knot in the rope the tension is... more
Which force is responsible for victory in tug of war?
I'm confused: In a tug of war game on rough ground who will win? The one who applies greater force on the rope or the one who applies greater force on ground?
Understanding the trajectory of a projectile?
It is stated that a projectile's motion can be divided into individual vectors. Now according to the laws of physics, the forces acting in the y-direction will never cancel or affect the force... more
Rope tension question?
If two ends of a rope are pulled with forces of equal magnitude and opposite direction, the tension at the center of the rope must be zero. True or false? The answer is false. I chose true though... more
What is the cause of the normal force?
I've been wondering, what causes the normal force to exist? In class the teacher never actually explains it, he just says "It has to be there because something has to counter gravity." While I... more
Does an athlete's proficiency at luge depend on his mass?
I was watching the men's [luge](http://en.wikipedia.org/wiki/Luge) ride with my dad. My dad said, the mass of the athlete must be at an optimum level so that he wins. I said, his volume should be... more
Ball flying towards me or me flying towards ball?
Suppose a ball is flying towards me at a speed of 10m/s and that, on impact, I feel "x" amount of pain. If, instead, it was me flying towards the ball at the same speed, with all other conditions... more
Bidirectional jerk motion on a stopping vehicle?
A stopping vehicle (say a car) has an apparent retardation (which may/may not be constant in magnitude) when force via brakes is applied. I travel by subway trains, and I noticed an odd... more
Do two springs compressed springs placed against each other obey Newton's third law?
I've been mulling over the following scenario. Say I take two springs whose force is given by some well-defined function of position (for example, Hooke's law F=kx will do). Using this law, I... more
How could a cord withstand a force greater than its breaking strength?
How could a 100 N object be lowered from a roof using a cord with a breaking strength of 80 N without breaking the cord? My attempt to answer this question is that we could use a counter weight.... more
How do I describe and calculate the effect of an impacting object?
My lab studies the physiology of impact injury on biological tissues. I use a pneumatic cylinder to impart injury into a biological sample and then assess the molecular and physiological changes in... more
How can tangential acceleration from a radial force be explained?
A mass is attached to a rope, and put into a circular motion. If I pull the string from the center, the tangential speed of the mass will increase (by conservation of angular momentum). I am... more
Calculating electric motor's weight lifting ability knowing power. What else do I need to know?
So, my company works with electric motors, and my boss wanted me to calculate how much weight could be lifted by a motor rated at 750W. I know that I can't just calculate the work done by it... more
Bounce of a ping pong ball vs bounce of other things (How does the material affect ?)?
Yesterday I saw that a ping pong ball bounced nicely on a hard surface but poorly on a mattress.On the contrary ,I saw that other things (a pen for example) bounced poorly on a hard surface but... more