Forces Definition and 1000 Threads

Homework Statement Explain why when a person in a canoe throws a package onto the shore, the canoe moves away from the shore? Homework Equations No equations, just Newton's third law. The Attempt at a Solution I think it's because the person applies a force onto the package and the package...

Homework Statement A skydiver is jumping out of an airplane. During the first few seconds of one jump, the parachute is unopened, and the magnitude of the air resistance acting on the skydiver is 251N. The acceleration of the skydiver during this time is 5.96 m/s^2 [down]. Calculate the mass of...

Homework Statement In the men's four-man bobsled event in the winter olympics, the maximum mas of a bobsled with pilot, two riders, and a brakeman is 630 kg. During a practice run, the rear rider and the brakeman exert average forces of 1220N and 1200N [forward] respectively to accelerate a...

Homework Statement This is not a specific problem, I was just wondering, what unbalanced force acts on your body when you are in a car traveling at a constant velocity and the car comes to a sudden stop? This has to do with Newton's First Law, but I'm unsure of what force applied to your body...

+ A man is holding a closed cage on the palm of his hand with a bird in it. When the bird flies with an upward acceleration inside the cage, it feels heavier. But the force due to the bird in the cage is actually an internal force on the cage, and internal forces don't cause acceleration of...

Homework Statement Two small objects of equal mass 3.0g are placed a certain distance apart. How many electrons must be transferred from one to the other so that the electric force between them is equal to the gravitational force between them? Homework Equations Coulomb's Law: F = K...

i calculated the centripetal forces in our solar system but i can't seem to find a connection using the centripetal force formula: Fmpz=(m⋅v2)/r i found out that the mean centripetal force for the planets around the sun is about 10^39, the mean centripetal of the moons around Jupiter is about...

While I was thinking about how tidal forces can make objects float at the surface of a planet orbiting a massive object like a black hole, the fact that any material on the Earth isn't held together by gravity only, but also by chemical bonds which give it its tensile strength came into my mind...

Homework Statement A 2000 kg plane is landing at an airfield with an initial speed of 50 m/s. The force of friction is 1/4 the weight of the plane. What is the acceleration of the plane? Homework Equations Fnet = ma Fnet = something - ff The Attempt at a Solution 2000a = thing I don't know...

Homework Statement I have here a problem asking me to find the tension force on the lower end of a rod with mass of 0.6 kg. The rod connects two blocks, the first / upper one has a mass of 5.0 kg while other/lower one has a mass of 4.0 kg. There is an upward force of 150 N applied on the whole...

Homework Statement a)ii) Calculate the upward force F acting on Baumgartner at this point. (3 marks) total mass of Baumgartner = 95 kg g = 9.8 ms-2 b) Describe the shape of the graph between 30s and 70s. Explain the velocity changes in terms of changes in the air through which Baumgartner was...

Homework Statement Why is potential energy variation between two points equals to the work of the opposite of conservative forces between these two points? Homework Equations If we call these forces $$\vec F_ext^C$$ \begin{equation} \Delta E_p=E_p(B)-E_p(A)=-\sum W_{A\rightarrow B}(\vec...

why the Fx is given by the formula = ρ AV1 ( V1 - V2 cos θ ) , why not = ρ A( V1 - V2 cos θ ) ?

I've come to understand that intermolecular forces cause the boiling point of hydrochloric acid solutions below 20% to be higher than the boiling point of water. I also understand that dissolving hcl in water is an exothermic reaction. But, what about those intermolecular forces. I assume they...

Homework Statement An object slides across a table at a constant 8.0 m/s to the right. The net force is... A) zero B) equal to the weight C) equal to the mass times the velocity D equal to the friction force Homework Equations N/A 3. The Attempt at a Solution Bu narrowing it down i don't...

Homework Statement A particle is been acted by a central force exerted by a sphere of mass 'M' at a distance 'xo' initially from the particle (of same mass). At t=0 the particle has velocity Vt perpendicular to the line joining the particle and the center of the sphere. Find the time at which...

Homework Statement In outer space, a ball with mass 0.25kg and charge +4/K C is shot from 5m towards a +0.5C charged ball with an initial velocity of 20 m/s What main Physics principle should be used to solve this problem? What is the closest the small ball will get to the large one? What is...

Homework Statement A motorised model plane is attached to a light string anchored to a ceiling. The plane follows a circular path of radius 0∙35 m as shown in Figure 2. The plane has a mass of 0∙20 kg and moves with a constant angular velocity of 6∙0 rad s−1 . (a) Calculate the central force...

Hi, two questions: Does the same energy put into an attraction force give the same force as a repulsion force? I am wondering if one is measuring slightly weaker than the other. ie. If I measure the positive/negative attraction force, is the positive/positive repulsion force as strong when...

Homework Statement Homework Equations ∑Fx=0 ∑Fy=0 ∑M=0 The Attempt at a Solution [/B] I am just concerned with part a. I got the correct answers doing this: First, FBD of segment AB: +cw ∑M_A=0: -136 - 6*By = 0 By = -22.7N two ways to get Ay: one: +cw ∑M_B=0: -136 + 6*Ay = 0 Ay =...

Homework Statement We have a slab with uniform distrubuted load on it W. All dimensions. [/B] I'm looking for the force on the bolts and force on the hook contact surface. The Attempt at a Solution My way to do it is to reduce the problem for 2D. But the problem is that I'm not sure how to...

I was confused about this example from a book. After putting in some numbers I got the forces circled in green and blue to be negative. Does this mean the directions for the forces shown is incorrect, and so I should switch the directions before calculating the reaction forces in the bearings (x...

Homework Statement When the piston CD is lowered, ACB and CBE are horizontal, and they ask for the force in piston CD. Homework EquationsThe Attempt at a Solution So first we look at the entire frame ACDBE, and we sum moments at A: -(14)(2500) + 24E(suby) = 0; E(suby) = 1458 Then A(suby) is...

Homework Statement Hello, we were given homework, which is perfectly described by this picture. We should figure out F1 and F2 (it's number). I know that if the both angles are equal, it is easy to solve. However, now i should solve a situation when first angle (alpha) = 50 grades, the second...

Homework Statement Charge is distributed on the surface of a spherical balloon (an insulator). A point particle with charge q is inside. If polarization effects are negligible the electrical force on the particle q is greatest when: a. it is near the inside surface of the balloon b. it is at...

Homework Statement I'm asked to find whether the object is moving or not in this question , i was given the solution like this , i am wondering why the tension from 100kg to the roller(up) and the tension from point B to roller doesn't cancel each other?[/B] Total force acting down the slope...

Example of a tightrope walker: Now, the weight force acts at a point. The rope is stretched. Compressive forces act inwards towards that point (opposite to TL and TR, the tensile forces). The resultant of the compressive forces equals the weight and is in the same direction – the weight force...

If a body is falling downward under the effect of gravity(=mg) and someone applies a force(=mg) in the opposite direction (upward), then the body will continue moving downwards as the net force is zero. What would be the magnitude of the force applied such that the body would freeze in midair(if...

Homework Statement A skier of mass 70 kg is pulled up a slope by a motor-drive cable. a. How much work is required to pull him 60 m up a 30° slope (assumed frictionless) at a constant speed of 2 m/s? b. What power must a motor have to perform this task? Help would be greatly appreciated...

Homework Statement A rope of negligible mass passes over a pulley of negligible mass attached to the ceiling, as shown above. One End of the rope is held by Student A of mass 80 kg, who is at rest on the floor. The opposite end ofthe rope is held by Student B of mass 70 kg, who is suspended at...

Homework Statement Block A has a mass of 75 kg and is initially at rest on a frictionless inclined plane tilted at a 37 ° above the horizon. Block A is attached to a massless rope that is connected to the top of Block B by way of a massless frictionless pulley. Block B also has a mass of 75 kg...

Okay here is my question. Assume that you are pulling a spring with 3N from one end and 5N from the other one. How can we apply Hooke's Law in this case? And let's assume that the spring isn't stretching anymore just to simplify things, but it is accelerating. If we divide the spring into...

I sketched out a slightly simplified model. It is a cantilever rod with two supporting rods of slightly larger diameter, connected by a plate. (Ignore the weight of the individual parts. For illustration purposes, I draw this to resemble a cantilever beam from the side view but in actual design...

I read somewhere that on the scale of the solar system, all forces except gravity are negligible. I can't think of any forces except gravity that would be acting on the planets... what are these other negligible forces?

Homework Statement If two parallel rods are placed 1mm apart, with one directly above the other, each carrying a current I in opposite directions, of length L what is the mass of the upper rod as to balance the force Homework Equations F=ILxB[/B] The Attempt at a Solution I have little idea...

Homework Statement A sky driver reaches his terminal velocity of 373 ms^-1 and deploys his parachute at a height of 1500m, the drag force =bv^2 and weigh can be ignored. Find an expression for velocity as a function of distance traveled from the point the parachute was deployed The Attempt at...

Hi, i would like to know how to do this question for fluid mechanics. Sorry as I am new i didnt know how to upload images so i just uploaded the image in justpaste, here is the link http://justpaste.it/pz7r

Hello I hope you know the phenomenon called "Magnetic train". My teacher used it in classes to demontrate electromagnetic phenomena. So he told the advanced learners (however, here I am xD) to investigate it, especially the forces and how certain parameters affect the velocity. But I do not...

1. An object of mass m = 1 kg is initially placed on a frictionless plane, inclined by an angle θ = 30o as indicated below. How long does it take the mass to move the distance of 10 m down the incline?2. I had a question if how I solved this is correct. I got the right answer and I wanted to...

Homework Statement Determine the components of the forces acting on each member of the pin-connected frame shown. (the frame shown is drawn as a free-body diagram in the image provided below (the top-most portion) and is correct) Homework Equations Equilibrium equations: ∑M=0 ∑Fx=0 ∑Fy=0 The...

Another classic case of "I understand it in reality, but on paper it just makes no sense and I'm confused". There is an object sliding north on a surface where the normal is 10N. The co-efficient for kinetic friction for the surface is 0.5. Simple math will tell me that the force of friction...

Homework Statement A 500-kg concrete slab is supported by a chain and sling attached to the bucket of the front-end loader shown. The action of the bucket is controlled by two identical mechanisms, only one of which is shown. Knowing that the mechanism shown supports half of the 500-kg slab...

I have attached a picture so that it is easier to visualize this problem. The information is all in it. The number scribbles are just my attempts to solve it: http://i65.tinypic.com/2qlbn9h.jpg The current topic we are on in class is Newton's Laws and we have covered moments and equilibrium...

Homework Statement A particle travels 27 degrees to the y axis, a magnetic field travels parallel to the y axis. In which direction is the magnetic force. Homework Equations Thumb=direction of q Fingers=direction of field palm=direction of force The Attempt at a Solution Basically how do I...

Homework Statement [/B] A ball rests in a trough as shown in figure. Determine the angle of tilt ##\theta## with the horizontal so that the reactive force at B will be one-third at A if all surfaces are perfectly smooth. 2.Relevant equations Application of Lami's theorem and some algebra...

So I have to do this question and I attempted this. Can anyone go over this and see if I did it correctly. Another student from my class told me I had to use the torque in order to calculate Fab but I don't see how I would do that.

Homework Statement Three uniform spheres are fixed at positions shown in the figure. i) What is the magnitude of the force on a 0.0150-kg particle placed at P? ii) What is the direction of this force? iii) If the spheres are in deep outer space and a 0.0150-kg particle is released from rest...

A 10.0 kg object is released from the top of an incline with a height of 1.00m. The incline makes a 15.0 degree angle with the horizontal. If the speed of the object is measured to be 3.00m/s at the bottom of the incline, what was the constant frictional force (Fk) along the incline? I have...

Hello everyone, I am trying to find out how space elevators work, but there is one think I can't figure out. Normally, the forces on the countermass and it's tether will be as following, assuming you neglect the gravity on the tether. But now, I put the lift somewhere on the cable (below...

First of all, I am not from English-using country so excuse my short english skill. This is the question from Halliday. I have solved this problem and checked the answer from my reference which started its statement with below F + Fn − (m + M)g = (m + M)a where m = 0.250 kg is the mass of the...