Explore BrainMass


Theory of ballpoint pen.

Describe the energy changes that take place when a ballpoint pen is used. Decribe the forces that act in the use the ballpoint pen..

Mass Moment of Inertia of the Pulley

At the instant shown in the figure, the stepped pulley rotates clockwise at 25 rad/sec, with a clockwise angular acceleration of 6 rad/sec^2. The masses of the two blocks are mA = 0Kg, ma = 5Kg, and the cables are inextensible. Find the mass moment of inertia of the pulley. (See attached file for full problem description)

Two People Carrying a Mass Along an Inclined

Assume that W = 1.80 m, L = 3.30 m, angle = 21.0°, and that the weight of the mass is 39.90kg. What is the (vertical) weight carried by the builder at the rear? How do I set up the problem??

Rotational Motion: Wheel is pulled on a curb.

(See attached file for full problem description with diagram and values) --- You are trying to raise a bicycle wheel of mass and radius up over a curb of height . To do this, you apply a horizontal force . 1. What is the least magnitude of the force that will succeed in raising the wheel onto the curb when the

Zero Net Torque Conditions

Please see attachment for torque diagrams. Each of the four bars shown can rotate freely in the horizontal plane about its left end. For which diagrams is the net torque equal to zero?

Torque and potential energy in a current carrying coil

4) A circular coil with area A and N turn is free to rotate about a diameter that coincides with the x-axis. Current I is circulating in the coil. There is a uniform magnetic field B in the positive y-direction. Calculate the magnitude and direction of torque and the value of the potential energy U, as given in the equation; "U

For and troque acting on a current carrying coil

3. A rectangular coil of wire, 22.0 cm by 35.0 cm and carrying a current 1.40 A, is oriented with the plane of its loop perpendicular to a uniform 1.50 T magnetic field as shown below. a) Calculate the net force and torque which the magnetic field exerts on the coil. b) The coil is rotated through a 30.0º angle about the axis

Shear stress problem

Shear stress problem -------------------------------------------------------------------------------- My answer to question 5 is wrong, can you correct? PCD = pitch circle diameter Factor of safety = ultimate tensile stress / safe working stress

Torque and angular acceleration

Find the mass of a uniform solid cylinder which is mounted so that it can rotate freely (i.e., without friction) about a fixed axis that passes through its center and runs along the length of the cylinder. This is not a simple project because for one thing, that cylinder is heavy! Also you don't want to risk removing the heavy c

Angular Acceleration of a Roller

A roller is rolled by pulling on a rope wrapped around an inner groove, as shown in attachment. If the roller rolls without slipping, the angular acceleration in rad/sec^2 of the roller is what? (See attached file for full problem description)

Circular Frequency of a Rod

A slender rod is pivoted at 0 which is a frictionless bearing. The circular frequency in rad/s at the rod for a small oscillation is? (See attached file for full problem description)

Physics Problem - A uniform, hollow, cylindrical spool

Please help with the following classical mechanics problem. See attached file for full problem description. --- A uniform, hollow, cylindrical spool has inside radius R/2, outside radius R and mass M as in the attached .jpg. It is mounted so that it rotates on a fixed horizontal axle. A counterweight of mass m is connecte

Motor Torques

Q1) Assume the torque stays constant at 120 N-m. How long will it take for the unloaded armature to accelerate from zero up to full speed of 3000 rpm? Now I am given the formular Ix = I w-wo / t. All I know is that the rotational inertia is 2.81 kg-m^2. Q2) What will be the power of the motor when it is s

Circular Motion

A particle of motion is moving in such a way that its position at time t is given by (t^3-3t, 4t^2, 5t)....

Dipole Moments

Please show all work and show all equations used so I can understand completely. 1) A uniform electric field of 300N/C makes an angle of 25 degrees with the dipole moment of an electric dipole. If the torque exerted by the field has a magnitude of 2.5*10^-7N.m, the dipole moment must be ___? 2) The dipole moment of a dip

Solving a Rigid Body Problem Ssing Newton's Second Law of Motion

A car has a mass of 1.4 tonnes. The distance between the front and rear wheel axles is 3.6m and the centre of mass is positioned 1.5m behind the front wheel centre and 0.8m above the road level. These details are attached in Figure Q1. The car, initially travelling at 12.6km/h, is accelerated up a straight road inclined at 1

Circuit analysis and efficiency

A fully loaded 440V, three phase motor draws 12.4A at 86% power factor (pf). Its speed is 1730 rpm and its torque output to a mechanical load is 29.1 lb-ft*1.356=39.5Nm. What is the output HP and the efficiency?

Power Screws

A power square thread screw has a pitch diameter (dm) of 34mm, the lead of the screw 1 of 4mm, the frictional diameter of the collar (dc) of 40mm. The coefficients of friction are f=0.08 for the threads and fc=0.05 for the collar. the vertical load F per screw is 5 kN. How do I find the torque required to raise the load?

Free Body Diagram of a Crane

In the crane shown in the figure, the member BG weighs 600lb, which is considered to act midway between B and F. If other weights of members are neglected, what will be the forces in the two tension rods? What will be the horizontal and vertical components of the reactions at A and B? Please see attached.

Solve: Computing the Torque

A force of 30N is applied perpendicularly to the face of a door at a distance of 1.5 m from the hinge of the door. Find the torque on the door about its hinge: a. 20 n/m b. 2nm c. 45Nm d. 20Nm

Solving for Angular Accelertion

Question: F=1 N and the length of the rod is L=1m. Find the angular acceleration when theta=0, 45, and 90 degrees. (I=1/12mL^2) m=1 kg

Stress Conditions, Etc.

A simple explanation of these solutions would be much appreciated. Could you also include any relevant comment along the way to help me understand your method and this subject better? Sketches are required. Can you also include Mohr's circle? Please find the questions in the attachment below. Hope you can help with this revis

Tension weight

A 20.0 ft horizontal arm is uniform and weighs 50.0 lbs. Find the tension in the cable and the horizontal and vertical forces at the hinge for a load of 500 lbs located 5.00 ft from the right end as shown.

Rotational Dynamics and Net Torque

A 10 kg solid disk of radius 0.50 m is rotated about an axis through its center. If the disk accelerates from rest to an angular speed of 3.0 rad/s while rotating 2.0 revolutions, what net torque is required?

Magnitude of Force Applied to a Wooden Board

A force is applied to the end of a 2ft long uniform board weighing 50lbs, in order to keep it horizontal, while it pushes against a wall at the left. If the angle the force makes with the board is 30 degrees, the magnitude of the applied force F is... a. 28.9lb b. 50lb c. 100lb d. 57.7 lb

Output Horsepower and Efficiency

A fully loaded 440 V, three phase motor draws 12.4 A at 86% power factor (pf). Its speed is 1730 rpm and its torque output to a mechanical load is 29.1 lb-ft x 1.356 = 39.5 Nm. What is (a) the output horsepower and (b) the efficiency?

Strength of Materials

1. A solid round steel shaft 3 1/2 inches in diameter transmits 100 HP at 200 RPM. Determine: a. Torsional stress in the outer fibers b. Angle of twist per foot of shaft c. Increase in stress at the outer fibers if the shaft is made hollow with a 1 1/2 inch bore. d. Stress at the inner fibers of the hollow shaft. e. Angle

Calculating Output Voltages

A steel tube, 24mm OD and 20mm ID is used to create a torque sensor. Four gauges are fitted to the tube in a bridge configuration and the bridge is supplied from a 10V source. Gauge Factor = 2.125 Shear modulus for steel = 82GN/m^2 Young modulus for steel = 210 GN/m^2 Max shear strain = 1000x10^-6 What is the output vo