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    Find the reactions the pin A and roller D exert on the truss

    Homework Statement The rigid truss supports the loads shown. Find the reactions the pin A and roller D exert on the truss. All concentrated loads act on the pins joining the truss members Homework Equations ƩMa= -5ft(3kips)-10ft(2kips)-.707(1kip)10ft+Dy(15ft) Dy=2.80 kips*ft The Attempt...
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    Double integral finding the area

    Homework Statement Use a double integral to find the area of the region bounded by the curve r= 1+sin(theta)? Homework Equations The Attempt at a Solution I can't figure out what theta is intregrated from. I've tried from -(pi)/2 -> +(pi)/2 and that doesnt work. I've also tried...
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    Find point d on the line l closest to point c

    Homework Statement Find point d on the line l closest to the point c (1,1,7). Point c is on the end of a vector who's origin (1,1,2) is on line l. There is an imaginary line that connects point c to point d. This imaginary line is perpendicular to the line l. This problem is relating to...
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    How do I draw a line that is 50 deg west or 15 deg east etc

    [b]1. Homework Equations The Attempt at a Solution
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    How to get a dc power supply to produce 2V at 10-20 milliamps?

    I just got a adjustable dc power supply and I cannot figure out why it will not produce 1-2V at very small amps such as 10-20 milli amps? Is this not possible with a common dc power supply? I would greatly appreciate some help with this...
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    What is the integral 1/x log(x) or lnx?

    Homework Statement I know it is supposed to be lnx however I find something peculiar. When I integrate it in wolfram alpha they give the integral as log(x). What the heck is going on here!?! Homework Equations The Attempt at a Solution
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    Intersection of two graphs

    Homework Statement The graphs y=abs(x) and y=(x^2)-6 intersect at x=3 and x= -3 What is confusing me is when I set them equal to eachother and solve (x^2)-x-6=0 and (x^2)+x-6=0 I get -3,+3,-2,+2 What is the deal with the negative 2 and pos 2? Homework Equations The Attempt...
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    Simple integration problem

    Homework Statement Find the area between f(x)=(x-1)^3 and f(x)=(x-1) on the interval from 0 to 2. Homework Equations The Attempt at a Solution Working it out Im using the top function minus the bottom function from 0 to 1 and then from 1 to 2. The graphs cross at x=0,x=1,andx=2...
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    Emf of a battery

    Homework Statement determine the terminal voltage in each battery. Emf1=18V r1=1 ohm EMF2=12V r2=2 ohm R=6.6 ohms also the batterys currents are opposing each other. Homework Equations Vab=emf-Ir The Attempt at a Solution i used kirchnoffs rule to find the current I ...
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    Double slit experiment

    My question is about the double slit experiment..I was just listening to a guy explain this experiment on youtube and I got skeptical at one point in his explanation. He said that when the photons went through the double slits the detectors were turned" on" then the observers viewed the results...
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    Centripetal force prob

    Homework Statement prob1) For a car traveling with a speed v around a curve of radius r, determine a formula for the angle at which a road should be banked so that no friction is required. prob2)Calculate the frictional force needed for a 900kg car traveling around a 500m radius curve at...
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    Conservation of momentum prob

    Homework Statement A wooden block is cut into two pieces, one with three times the mass of the other. A depression is made in both faces of the cut, so that a firecracker can be placed in it with the block reassembled. The reassembled block is set on a rough-surfaced table, and the fuse is...
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    Torque prob

    Homework Statement A 7.5 m long uniform aluminum pole with a mass of 12.0 kg supports a 21.5 kg traffic light. The aluminum pole is attached to a vertical pole by a pivot near the base. A massless horizontal rope supports the aluminum pole and is connected to the vertical pole 3.80 m above...
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    Rotational motion

    Homework Statement A hoop rolling on a horizontal surface with a speed v=3.3m/s when it reaches a 15 deg incline.How far up the incline does it go?How long will it be on the incline before it reaches the botttom? Homework Equations I=mr2 conservation energy going up=2gyf=r2+vi2...
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    Cabbage chemical composition?

    cabbage chemical composition??? Does anyone know what the chemical composition of cabbage is??? I've looked all over the internet and cant find ANY information on this.
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    Moment of inertia and rotational kinetic energy

    Homework Statement A merry-go-round has a mass of 1640 kg and a radius of 7.50 m. How much net work is required to accelerate it from rest to a rotation rate of 1.00 revolutions per 8.00s? Assume it is a solid cylinder. Homework Equations \DeltaKE=Wnet=1/2(Iw2)=14211.7J...
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    Rotational dynamics prob

    Homework Statement A grinding wheel is a uniform cylinder of with a radius of 8.50 cm and a mass of 0.580 kg. Calculate a) its moment of inertia about its center, and b) the applied torque needed to accelerate it from rest to 1500 rpm in 5.0 s if it is known to slow down from 1500 rpm to rest...
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    Moment of inertia and rotational kinetic energy prob

    Homework Statement A spool of wire mass m and radius r is unwound under a constant force F. Assuming that the spool is a uniform solid cylinder that does not slip, show that the acceleration of the center of the mass is 4F/3m Homework Equations F+f=ma f=ma-F \tau =I\alpha=Fr-fr...
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    Merry go round, rotational dynamics

    Homework Statement A plyground merry go round of radius r=2m had a moment of inertia of I=250kg/m2 and is rotating at 10rpm about a frictionless verticle axle.Facing the axle a 25kg child hops onto the merry go round and manages to sit down on its edge.What is the new angular speed of the...
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    Rotational dynamics problem

    Homework Statement A uniform solid cylinder and a uniform cylindrical shell are placed side by side at the top of an incline.If they sre released from rest and roll without slipping, A)Determine their speeds when they reach the bottom B)Which objet reaches the bottom first? Homework...
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    Child bouncing on pogo stick-harmonic motion

    Homework Statement Estimate the stiffness of a spring in a childs pogo stickif the child has a mass of 35kg and bounces every 2 sec. Homework Equations x=Asin(wt) w=2(pi)f w=2pi/T F=mg-kx=ma U=1/2kx2 E=1/2mv2+1/2kx2 The Attempt at a Solution The equations that are listed are...
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    Rotational motion problem 2

    Homework Statement At a particular moment in a race, a car moving around a turn with a radius of 50m had an angular speed of .6rad/sec and an angular acceleration of .2rad/sec2 At this particular moment find: the linear speed the centripetal acceleration its total linear acceleration...
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    Rotational motion problem

    Homework Statement A centrifuge rotor is acceleratedfrom rest to 20,000 rpm in 5min. Through how many turns has the centrifuge rotor turned during its acceleration period?Assume constant angular acceleration. Homework Equations The Attempt at a Solution I just concluded that it...
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    Rotational motion equations

    Homework Statement My lab book list these four Rotational motion equations and does'nt say what they are. Could someone please tell me what each equation is and what they are used for. thanx Homework Equations \theta2-\theta1=(w1+w2)(t2-t1)/2 w2-w1=alpha(t2-t1)...
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    Simple harmonic motion of an ideal spring

    simple harmonic motion !!!!!!!!!!!!! Homework Statement An ideal spring has a spring constant k=25N/M and is suspended vertically. A 1kg object is attatched to the unstrechted spring and released. It then performs ocillations. What is the magnitude of the acceleration of the body when the...
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    Ball dropped, elastic collision, harmonic motion

    Homework Statement A ball dropped from a height of 4m makes a perfectly elastic collision with the ground. Assuming that no energy is lost due to air resistance. show the motion is periodic determine the period of the motion Homework Equations yf-yi=vit+1/2ayt2 a=-(w2)x a=9.8m/s2...
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    Amplitude and period harmonic motion

    Homework Statement Im confused about what exactly is the period and amplitude of a spring.... Is the period -during ocillation-from top to bottom back to top? or vice versa. and is the amplitude 1/4 of the period? Homework Equations The Attempt at a Solution
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    Simple harmonic motion problem

    Homework Statement An ideal spring has a spring constant k=25N/M and is suspended vertically. A 1kg object is attatched to the unstrechted spring and released. It then performs ocillations. What is the magnitude of the acceleration of the body when the extension of the spring is at maximum...
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    Spring force

    Homework Statement I just have a question about the force of a spring. Since the force of a spring force is a conservative force, is there a conservation equation for springs? Also, when a mass is put on a spring and it streches out fully, at this point velocity is zero and potential energy is...
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    Internal explosion problem

    Homework Statement an internal explosion breaks an object, initially at rest, into two pieces, one of which has 1.5 times the mass of the other. If 7500 J were released in the explosion, how much kinetic energy did each piece acquire. Homework Equations K1+K2=7500J...