Tagged Questions
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0answers
50 views
Work And Energy Question [closed]
$H = 3\text{ m}$,$m=2\text{ kg}$
The right side is rough.
I want to figure:
what is the coefficient of friction $\mu$?
How high and exceed the maximum return on the plane right body?
I know ...
0
votes
0answers
40 views
Work required to pull capacitor plates apart when connected to battery [closed]
For (a), I just use $F = k \frac{Q_1 Q_2}{r^2}$, then (b) $W = - \Delta U = - qE \Delta d$, correct so far? But how do I do (c)?
0
votes
0answers
36 views
What is the total work done in this problem? [closed]
A 1800 kg trick airplane is 450 m in the air. At this point the plane takes a dive
with an initial speed of
42 m/s and accelerates to 64 m/s, dropping
a total distance of 120 m.
(a) Using the ground ...
0
votes
1answer
60 views
How to find work done due to friction [closed]
The force F=40N is applied on a 10kg block at an angle of 36 with the horizontal. The block moves a distance of 15m. If the surface is frictionless. If the coefficient of kinetic friction is 0.25, ...
2
votes
1answer
56 views
Work done by gravity on Water
Now according to me we would see change in potential energy of system and equate it to the work done by gravity.
But when we see this the first column lowers by $H/2$ and right one rises by $H/2$ ...
0
votes
1answer
33 views
Work done by complex field on complex plane
A force field is given by $F = 3z+5$. Find the work done in moving an object in this force field along the parabola $z = t^2 + it$ from $z = 0$ to $z = 4+2i$.
I don't understand why conjugate ...
0
votes
2answers
102 views
How do you tell what forces do no work?
The total mass of the children and the toboggan is 66 kg. The force the parent exerts is 58 N (18 degrees above the horizontal). What 3 forces/ components do no work on the toboggan?
I said the ...
0
votes
1answer
68 views
About the work done by gravity to pull the object down to the earth surface
The following question is from an physics exercise and I know the answer and the way to solve the problem but just curious why my own way doesn't work. The question is asking "A 2500kg space vehicle, ...
1
vote
3answers
160 views
Integration by parts to derive relativistic kinetic energy
I have come across a weird integration during derivation of relativistic kinetic energy. Our professor states that i can get RHS out of LHS using integration by parts:
$$
\int\limits_0^x \! ...
0
votes
0answers
46 views
Work, energy and friction [closed]
A car loaded with bricks has a total mass of 18kg and is pulled at a constant speed by a rope. the rope is inclined 30 degrees with above the horizontal, and the cart moves 20.0 m on a horizontal ...
1
vote
2answers
143 views
Finding maximum speed in a work-energy problem
I have the following problem:
The Royal Gorge bridge over the Arkansas River is $310\text{ m}$ above
the river. A $57\text{ kg}$ bungee jumper has an elastic cord with an
unstressed length of ...
1
vote
0answers
40 views
Problem in average height
Let, diameter of cylinder hole of height 30m and diameter 2m filled with water. In a book, when author tried to find out the power for lifting all of the water then he used average height. why is ...
3
votes
2answers
119 views
Find work done by force along a path - is parameterization the only way?
$F = x^3y^4 \hat i + x^4y^3 \hat j$ from $(0,0)$ to $(1,1)$.
I am given different paths.
For example, "first along x axis and then along the y axis" is one of the paths.
Is this problem solvable ...
1
vote
1answer
151 views
Work done in projectile motion
A projectile is shot at some inclination to the ground. It falls at another point having R distance from the initial point on the ground. Is there any work done?
If initial velocity vector is $(u\cos ...
3
votes
4answers
575 views
Why does an object thrown parallel to the ground eventually fall down?
Suppose an object is thrown parallel to the ground. The gravity acts downward (ie. perpendicular to the direction of motion of the object). The work done by gravity on that object will be given by :
...
-1
votes
2answers
348 views
Work done by the air resistance [closed]
A ball of mass 0.37 kg is thrown upward along the vertical with a
initial speed of 14 m / s, and reaches a maximum height of 8.4 m.
a) What is the work done by air resistance on the ball? b) ...
0
votes
1answer
131 views
Is resistance to motion directly proportional to the speed of a moving object?
Power is known to be equal to the force x velocity (P=FV).
Im solving a question that states the following :
Car with engine working at 32 kW, mass of 1 tonne, travels at a constant speed of 40m/s ...
1
vote
2answers
182 views
Mechanics Question: Energy, Work and Power
I'm a pure mathematician by trade, and have been trying to teach myself A-level mechanics. (This is not homework, it is purely self-study.)
I've been working through the exercises and have come up ...
2
votes
1answer
125 views
Understanding Work and the conservation of energy
We have a car with a mass of $780 kg$ with travels with a speed of $50 km/h$. The car brakes and after $4,2m$ is stops completely. Warmth is created. Calculate the friction.
I solved this easily, by ...
1
vote
2answers
304 views
Calculating force required to stop bungee jumper
Given that:
bungee jumper weighs 700N
jumps off from a height of 36m
needs to stop safely at 32m (4m above ground)
unstretched length of bungee cord is 25m
Whats the force required to stop the ...
1
vote
1answer
389 views
Needed Energy For Lifting 200 kg weight
I'd like to learn how much energy I need to lift a 200 kilograms weight on normal earth conditions?
For example how much electric power do we need?
I'm not a physicist and not a student and this ...
0
votes
3answers
247 views
A chain 64 meters long whose mass is 20 kilograms is hanging [closed]
A chain 64 meters long whose mass is 20 kilograms is hanging over the edge of a tall building and does not touch the ground. How much work is required to lift the top 3 meters of the chain to the top ...
1
vote
1answer
261 views
ratio between work and heat [closed]
I am really stuck on a problem in my textbook:
Water is heated in an open pan where the air pressure is one atmosphere. The water remains a liquid, which expands by a small amount as it is heated. ...
2
votes
3answers
960 views
How do I find work done by friction over a curve represented by a polynomial?
I am facing a problem in Physics.
Problem: What will be the work done by the frictional force over a polynomial curve if a body is sliding on this polynomial($a+bx+cx^2+dx^3+\ldots$) curve from rest ...
3
votes
1answer
341 views
I have a slight problem understanding the concept of “work”?
What I understand is that work is not the same as a car using gas or a crane lifting a car high up into the air. Let's use the crane as an example. And let me write out a few lines from the book.
...
2
votes
1answer
379 views
Does moving something horizontally in gravity do no work?
Bill’s job is to lift bags of flour and place them in the back of a
truck, which is parked next to him. Sally is loading the same bags of
flour into a similar truck that is located 10 m away. ...
1
vote
1answer
306 views
Work and Area under a Curve relating to Hooke's Law
If it takes work W to stretch a Hooke’s-law spring (F = kx) a distance d from its unstressed length, determine the extra work required to stretch it an additional distance d (Hint: draw a graph and ...
