Newton's second law Definition and 264 Threads

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...

I, earlier were studying Newton's second law F=ma, or rather the free fall of objects, F=mg. A thought occurred to me, how do I apply this formula to the moon with the Gravity of 1.622m/^2 and came up with F=m(g/6), however, g/6 = 1.63m/s^2 Normally I'd just use F=ma, but assuming people one...

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 A car travels along the perimeter of a vertical circle (radius = 0.25 km) at a constant speed of 30 m/s. What is the magnitude of the resultant force on the 60-kg driver of the car at the lowest point on this circular path? Question options: 1) 0.37 kN 2) 0.80 kN 3) 0.22 kN...

Homework Statement In an experiment, I measured the effect of mass on the acceleration of a cart, rolling down a leveled air track. I then graphed acceleration vs. mass (m'), where: m' = m / (M+m); M = mass of the cart, m = hanging mass, which was increased with subsequent trials. Homework...

Homework Statement Given the free-body diagram below, and that the body is in equilibrium, find θ. Homework Equations F = ma The Attempt at a Solution [/B] Basically, I used Newton's second law in the y direction. Here is my work: This does not seem like the correct answer, because the...

The Question: Using a simply pulley/rope system, a crewman on an Arctic expedition is trying to lower a 5.65-kg crate to the bottom of a steep ravine of height 23.9 meters. The 60.9-kg crewman is walking along holding the rope, being careful to lower the crate at a constant speed of 1.50 m/s...

Homework Statement Influenced by certain force, cart moved from place and driven 0.5 meters distance. When 200grams weight was placed on cart it moved 0.3 meters during the same period of time. Calculate the mass of the cart.

Hello, I am confused by the momentum version of Newtons second law... So we know \bar{F}=m\bar{a}=m\left(\frac{d\hat{v}}{dt}\right) and that \bar{\rho}=m\bar{v}=m\left(\frac{d\bar{x}}{dt}\right) so is \frac{d\bar{p}}{dt}=m\frac{d\left(\frac{d\bar{x}}{dt}\right)}{dt} What I mean is this...

Homework Statement In a laboratory frame of reference, an observer notes that Newton's 2nd Law is valid. Show that Newton's 2nd Law is also valid for an observer moving at a constant speed, small compared with the speed of light, relative to the laboratory frame. Homework Equations dx'/dt =...

We all know that f = m*a. But why can't we write this as f = m * s/t^2 ? I know this is wrong. But what is the reason?? Need opinion on this. Thankyou.

is there any derivation of Newton second law?

Homework Statement Homework Equations F=ma, Fr = μN The Attempt at a Solution 1kg(1m/s^2) = 1N Fnet = (x) - 1.18 1N = x - 1.18 x = 2.18N 2.18N/9.81m/s^2 = 0.223kg I know this is not right because I was told that in my calculations Fnet and Fr go in the same direction. Also I didn't use...

Homework Statement An airplane goes into a turn 3.6km in radius. If the banking angle required is 28 degrees from the horizontal, what is the plane's speed? Homework Equations Newton's Second. The only forces acting on the plane are gravity and the normal force. This isn't given in the...

1. A 92 kg water skier floating in a lake is pulled from rest to a speed of 12 meters/second in a distance of 25 meters. What is the net force exerted on the skier, with the assumption that his acceleration is constant?2. Force = Mass x Acceleration3. As far as I know, from using the equation...

Homework Statement A 2.60 kg block is initially at rest on a horizontal surface. A horizontal force F→ of magnitude 7.39 N and a vertical force P→ are then applied to the block (see the figure). The coefficients of friction for the block and surface are μs = 0.4 and μk = 0.25. Determine the...

Homework Statement Given that: theta_dot = 6 rad/sec m_A = 0.8kg u_k = 0.40 The problem also mentions that movement is at a constant angular rate so I think that means: r_doubleDot = 0 theta_doubleDot = 0 Lastly, at an instant: r_dot = 800mm/sec = 0.8m/sec 2. Homework Equations...

THIS THREAD HAS BEEN MOVED FROM ANOTHER FORUM BECAUSE IT IS HOMEWORK. BUT THERE IS NO TEMPLATE. Hi everyone, The problem gives that a particle moves in a circle with angular velocity ω. I know that r×ω=v, which is the velocity of the particle. However, I am told to differentiate and find τ=Iα...

So I was wondering how did Newton himself state his second law. One account I've read says that he first expressed it in the form that we refer to as impulse and momentum i.e. FΔt=mΔv. Today I was told that Newton never even wrote F=ma, and that the expression a=F/m is a much "Better" way of...

Homework Statement I am stuck on this problem: So the question is asking for F21, F12, F32, and F23. (That's the force by 2 on 1). The mass of m2 is variable. There are four cases where I need to solve for the forces: when m2 has mass of 3kg, 0.3kg, 0.03kg, and 0kg. The mass of m1 = 2.5kg, the...

Homework Statement Here's the problem: A particular racecarcan cover a quartermile track (402m) in 6.40s starting from standstill. Assuming that the acceleration is constant, how many "g's"(all i know is that it means accleration due to gravity) does the driver experience? If the combined mass...

Homework Statement A 1.0 kg box on a horizontal frictionless surface is accelerated by attaching a 1.5 kg mass as shown in the diagram. What is the magnitude of acceleration of the box?(Remember, both boxes accelerate.) Homework Equations F = ma The Attempt at a Solution I drew a free body...

In the derivation on Wikipedia, it says the following ## \frac{dv}{dt}=\frac{dv}{dx}\frac{dx}{dt}=\frac{dv}{dx}v = \frac{d}{dx}[\frac{v^2}{2}] ## How do they go from the second to last to last equation? I've been trying to understand, but I think I'm just looking over something incredibly simple.

NOTE: The following questions are not part of any homework assigned. This is part of finding extra concept-related questions to help me study for my physics unit test. Homework Statement I have conceptual questions, not problems. I'll provide sufficient evidence that I've attempted to think...

I'm reading Halliday's chapter or rigid body rotation. In the derivation of Newton's second law for rotation, it is assumed that the object is hinged about some axis ( the connection would be a frictionless pin). The law is derived for such a connection, but is later applied to objects that...

Homework Statement Three blocks in contact with each other are pushed across a rough horizontal surface by a 98 N force as shown. The acceleration of gravity is 9.8 m/s^2. ----F--->|2kg| |7.7kg| |9.2kg| u = 0.082If the coefficient of kinetic friction between each of the blocks and...

As the title says, can there be any rotation if only one force is applied to an object at rest. For instance, if I had a rod laying flat on a frictionless surface, and I pushed one end, am I correct to say that Newton's second law says that all of that force goes into acceleration the center of...

Homework Statement Estimate the average force exerted by a shot-putter on a 7.0-kg shot if the shot is moved through a distance of 3.0m and is released with a speed of 10m/s . Homework Equations F=ma Maybe the Five Equations for constant acceleration? The Attempt at a Solution So my guess is...

Homework Statement (This is a problem I made up, so if the problem is with the problem, let me know.) A 500N ball is being pushed down a carpeted decline of 24° to the horizontal. It starts from 1 m/s and ends the 20 foot (6.1 m) decline at 32 m/s. What is the coefficient and force of kinetic...

Homework Statement I'm trying to create a problem for my physics standards that is hard. I gave myself a ball being pushed down a carpeted decline at 24° from the horizontal. The balls starts with an initial velocity of 1 m/s and ends the 6 meter decline at 5 m/s. I want to find the applied...

Recently, I've been pondering deeply on relativity (both Galilean and SR) and all of a sudden I find that I don't grasp even the basic concepts of physics (or life) anymore, i.e. I can't go back to my previous, "normal" mode of thinking. Consider Newtonian mechanics, take the ground to be at...

Very stupid question, but I am writing out my problem and need this formula; in typed symbols, so I can copy and paste it into my document. Like √ Hope that makes sense... Thanks!

Hello, I am a second year undergrad student majoring in Astronomy and Computer Science. I am having a hard time with my physics courses for the following reasons: 1) SmartPhysics is the text we use (if you can call it a text...). Basically it is an online HW and "pre-lecture" system that...

Renee is on Spring Break and pulling her 21-kg suitcase through the airport at a constant speed of 0.47 m/s. She pulls on the strap with 120 N of force at an angle of 38° above the horizontal. What is the normal force and the total resistance force (friction and air resistance) experienced by...

Homework Statement A 9 kg object is subjected to two forces, http://www.webassign.net/images/Farrowbolditalic.gif1 = 7 N i - 4 N j and [PLAIN][PLAIN]http://www.webassign.net/images/Farrowbolditalic.gif2 = 7 N i - 9 N j. The object is at rest at the origin at time t = 0. (a) What is the...

Homework Statement The 20.0 kg box is being pushed with a 45.0N Force acting at an angle of 25.0*. The coefficient of kinetic friction on this surface is 0.150. Find the acceleration Homework Equations F=ma Fy=0 Fx=0 The Attempt at a Solution So I attempted this so far (sum)Fy=0 Py+Fn-Fg=0...

Homework Statement A 0.17-kg cue ball rests on the pool table. It's struck by a cue stick applying force F1→ = 13Ni^+21Nj^ Determine the magnitude of the ball's acceleration. Homework Equations ax = Fnet, x / m ay = Fnet, y / m a = Fnet / m The Attempt at a Solution Components of...

With my understanding of Newton's second -- if I am going to use it to solve a problem, I would need to write ALL velocities in the system with respect to the lab frame (inertial rest frame) -- correct? Thanks, Chris

Does this solution mean anything ?

Definition/Summary Net force = rate of change of momentum (= mass times acceleration of the centre of mass, if the mass is constant) Net impulse = change of momentum These are vector equations, so they apply to each direction individually The rotational versions are: net torque =...

I know a high school student who has this question. My first thought was that it does not hold if the mass is changing with time. I was thinking of the situation of a snowball rolling down a mountain picking up more snow as it rolls to the bottom. There is obviously mass gained so does Newton's...

Homework Statement A 6.7-kg box is being lifted by means of a light rope that is threaded through a single, light, frictionless pulley that is attached to the ceiling. (a) If the box is being lifted at a constant speed of 2.0 m/s, what is the power delivered by the person pulling on the rope...

Homework Statement I'm trying to bridge F =ma to m/2(dv2/dx). It was shown in the course book I have but there's a huge disconnection in the steps. The Attempt at a SolutionF =ma = m.(dv/dt) = m(dv/dx . dx/dt) = mv(dv/dx). Where do I take it from here?

Homework Statement A cable is being used to lift a 350 kg piano into a helicopter. The cable can exert a maximum force of 5000 N without breaking. What is the maximum acceleration that the cable can give to the piano? Homework Equations w=mg The Attempt at a Solution w=? a=...

Homework Statement A 0.70-kg disk with a rotational inertia given by MR^2/2 is free to rotate on a fixed horizontal axis suspended from the ceiling. A string is wrapped around the disk and a 2.0-kg mass hangs from the free end. If the string does not slip, then as the mass falls and the...

Homework Statement A block of wood floats in fresh water with 0.722 of its volume V submerged and in oil with 0.895 V submerged. Find the density of (a) the wood and (b) the oil. Homework Equations mass = density x volume f = ma conservation of mass F_{weight} - F_{buoyancy} =...

Homework Statement "The constant force resisting the motion of a car of mass 1500kg is 980N. If, when traveling at 48kmhr-1, the car is brought to rest in a distance 50m by applying the brakes, find the additional retarding force due to the brakes (assumed constant) Homework Equations...

Homework Statement "A block of mass 10kg is pulled 20m up a smooth plane inclined at 45 degrees to the horizontal. The block is initially at rest and reaches a velocity of 2.0m/s at the tope of the plane. Calculate the magnitude of the force required, assuming it acts parallel to the plane."...

Homework Statement If m1=m2=1.0 kg and θ=30°, what will be the acceleration of the system? Calculate the tension in the cord, if a block m1 lying on a frictionless inclined plane and is connected to a mass less cord. Assume m1 is moving down the plane for A), and for B) m1 is in the opposite...

Homework Statement There is an attachment of a FBD, and you have to solve for the following: Fg=? Fnet? Mass=? The Attempt at a Solution I know you will have to equate equations, but I don't know how to go about doing this. I do know that Fg= m x 9.8, I isolated various equations and...