All Questions
32 questions
-2
votes
1
answer
89
views
Can we relate newton's second law and kinematics equations? [closed]
Specifically,
If vi = 0, then
a = vf^2 / 2s [ s = distance travelled]
And from newton's 2nd law,
a = Fnet / m [ m = mass of object]
But I've tried to them on a bunch of different problems, and they'...
- 811
2
votes
1
answer
113
views
What happens if I rewrite the acceleration in work formula this way?
Work is known as
\begin{equation}
W=\vec{F}.\vec{q},
\end{equation}
thus for a gravitational force $\vec{F}_g=m\vec{g}$ we have
\begin{equation}
W=mgh.
\end{equation}
My derivation is as follows:
\...
user330731
0
votes
2
answers
167
views
Linear Acceleration, Frames of Reference and the Laws of Physics
Alice and Bob, observers in deep Galilean spacetime, have identical rocket ships. Alice is at rest relative to an inertial frame. At $t=0$ she accelerates with acceleration $a_0$ in a straight line ...
- 75
0
votes
3
answers
707
views
How does negative velocity and positive acceleration exactly and vice versa slow down objects?
I am confused. How does negative velocity and positive acceleration and vice versa slow down objects? Here are my thoughts. Please let me know if I am correct.
According to Newton's first law of ...
- 137
0
votes
2
answers
2k
views
Can power to weight ratio be used to calculate theoretical 0-60 times?
The power to weight ratio is used to calculate how fast a car can accelerate. If a car has 400 hp and a weight of 2000 lbs (400/2000), it should make 0.2 hp per pound. If I switch the fraction around (...
0
votes
4
answers
392
views
Are there two normal forces here?
In this question the normal force direction on the collar was determined to the left, while there is a possibility to be to the right direction also since the collar contacts the rod in both ...
0
votes
2
answers
283
views
Is radial velocity parallel to radius of curvature or the position vector?
I'm a bit confused regarding the directions of velocities and acceleration in curvilinear motion. Assume a curvilinear motion, which is not circular. I know that tangential component of velocity and ...
- 337
4
votes
2
answers
312
views
Force and Accleration
It's just a basic question I had when I was studying physics years back,
So acceleration have two equations
$$a=\frac{F}{m}$$
and
$$a=\frac{\text{d}v}{\text{d}t}$$
So by the first equation, if I'm ...
- 171
1
vote
2
answers
849
views
Force creates the motion or Motion creates the force?
Motion Creates Force ?:
When you move your hand (to push a box for example), it creates a force.
When electron moves through a wire it creates electrical force.
Or Force Creates Motion ?:
Gravity ...
- 113
1
vote
1
answer
122
views
Velocity of particle due to acceleration. Special relativity
I understand how to do transformations of four velocities, acceleration and so on under Lorentz boosts. However after all I have learned in special relativity I still don't know how just an ordinary ...
- 25
0
votes
1
answer
209
views
Distance traveled by a particle in $n^{th}$ second
My book states that the distance traveled by a particle thrown upward in the last second is independent of it's initial velocity because the the object travels the same distance as a freely falling ...
user238497
0
votes
5
answers
733
views
Why do objects move back after collision?
When a ball collides with a wall, the ball moves in the opposite direction, why does this happen if Newton's third law operates. I mean the ball collided with the wall and imparted a force on it and ...
- 117
0
votes
1
answer
180
views
Acceleration in $x$ and $y$ directions of a pendulum swinging? [closed]
If there is a pendulum that gets released and only moves in two dimensions, what would it’s acceleration be in the x and y directions, meaning at what rate is the velocity changing in the x and y ...
50
votes
13
answers
24k
views
Why doesn't a braking car move backwards?
The net force on an object is equal to the mass times the acceleration, $F = ma$
When I brake on a (moving) car, the net force is negative, therefore causing the resulting acceleration to also be ...
- 637
2
votes
1
answer
125
views
Applying Kinematics to find retarding force in a medium
Question
If an object free falls let's say off a cliff that is 3 meters high, clearly it increases velocity and if at the bottom of the three meter there was a bucket full of jelly which created a ...
- 147
-1
votes
1
answer
248
views
Why is the speed of a rolling ball related to the incline?
Considering that the gravitational acceleration is constant and the air resistance is insignificant at low speeds, why is it that a ball rolls faster down a steeper incline?
- 11
0
votes
1
answer
1k
views
How can be Acceleration without force
Newton's first law says that everything will continue it's sate unless compelled by any external force. In my book it is written that "An object will continue accelerating until the resultant force on ...
- 253
0
votes
1
answer
1k
views
Elusive force opposing friction between passenger and seat in a decelerating car
A car traveling at 20m/s stops a distance of 50m. Assume deceleration is constant. The coefficient of static friction is 0.5 and coefficient of dynamic friction in 0.03. Will a 70kg passenger slid ...
- 104
2
votes
3
answers
5k
views
For circular motion in a vertical plane, why does Net Force = Centripetal Force?
I'm struggling with some of the concepts pertaining to the forces and acceleration associated with circular motion in a vertical plane (only concerned with what happens at the 'top' and 'bottom' of ...
1
vote
1
answer
175
views
Is dynamics only concerned with systems that are accelerating?
I'd just like to check my understanding of the branches of mechanics. I suspect dynamics is not just concerned with accelerating systems. Doesn't dynamics just generally deal with systems in motion? ...
0
votes
2
answers
1k
views
Do linear motion equations follow from any of the Newton's three laws?
The distance $x$ covers in time $t$ by a body having initial velocity $u$ having a constant acceleration $a$ is given by $x= ut+(1/2)at^2.$ Does this result follow from any of the Newtonian laws? ...
- 133
2
votes
0
answers
384
views
Calculating resultant force along vertical axis when using smartphone accelerometer [closed]
I'm making an app which is using accelerometer to automatically detect damages on the route while driving. To estimate if damage occurred or not I'm using accelerometer (acceleration along vertical y ...
0
votes
2
answers
69
views
Regarding Basic laws of motion
When a constant force is applied on body which is free to slide on a surface, does it move with a constant velocity after some time or does the velocity keep on increasing? Please explain it for both ...
- 21
3
votes
4
answers
2k
views
In perfect vacuum (no external force), if I apply a small amount of force to a body, will it continue to accelerate forever?
According to the equation $F = ma$, the greater the force applied to a body, the greater its acceleration. But in a place where there is no gravity or any other kind of external force, if I apply a ...
- 227
0
votes
4
answers
5k
views
Force required to send ball in set trajectory
If I have a desired 2D trajectory where I know the desired speed of my ball and desired path, and a ball that starts at (x=0,y=0), how can I calculate the required force / point at which the force ...
0
votes
3
answers
4k
views
Horizontal and vertical acceleration of a ball on a slope?
I understand that you resolve the components of the balls weight parallel and perpendicular to the slope in order to calculate the force due to gravity that actually acts down the slope.
The ...
- 1
0
votes
3
answers
350
views
Condition for 2 bodies to move together
The condition for 2 (or more) bodies to move such that they are always in contact, is that their accelerations (and velocities) along their common normal should be same.
Can someone explain why this ...
- 683
2
votes
6
answers
3k
views
Free fall into circular motion
If I'm on a roller coaster free falling from height $h$ and then suddenly start going into horizontal motion with a radius $r$ of turn what is the $g$-force I experience?
I worked out the equation ...
- 89
4
votes
3
answers
7k
views
Does a heavy body move with the slightest force on a frictionless surface?
If I apply horizontal force on a body resting on the ground, my force will be opposed by the frictional force and the body will accelerate at the point where my force exceeds the force of friction = $\...
- 207
-13
votes
3
answers
3k
views
What would happen if an unstoppable force hits an immovable object? [closed]
I realize that the question a rather large paradox, but I do wonder if such a thing were true what would happen, assuming that neither of these "objects" can be destroyed by each other?
- 305
12
votes
3
answers
1k
views
Is acceleration an average?
Background
I'm new to physics and math. I stopped studying both of them in high-school, and I wish I hadn't. I'm pursuing study in both topics for personal interest. Today, I'm learning about ...
- 873
1
vote
3
answers
34k
views
Calculating car's acceleration from change in angle of hanging object? [closed]
The question essentially is based on a situation like this-
A car has a small object hung from the cieling on a string (apparently at an angle of 0 degrees to the ceiling).
The car is accelerating ...
- 121