Explore BrainMass


Forces and Torques: Net torque applied to the cable car.

In San Francisco a very simple technique is used to turn around a cable car when it reaches the end of its route. The car rolls onto a turntable, which can rotate about a vertical axis through its center. Then, two people push perpendicularly on the car, one at each end, as in the drawing. The turntable is rotated one-half of a

Forces and Torques

You are installing a new spark plug in your car, and the manual specifies that it be tightened to a torque that has a magnitude of 47 Nm. Using the data in the drawing, determine the magnitude F of the force that you must exert on the wrench.

Torque on a loop

A rectangular wire loop with a cross-sectional area of 5,000 cm^2 carries a current of 0.50 amperes. The loop is free to rotate about an axis that is perpendicular to uniform magnetic field strength of 0.40 Tesla. The plane of the loop is initially at an angle of 25 degrees to the direction of the magnetic field. What is the ma

Angular acceleration of the rod

In problem 16.72(a), if the uniform slender rod weighs 15 lb, and the horizontal force P is 12 lb, the angular acceleration of the rod is: a. 44.2 rad/s^2 b. 82.8 rad/s^2 c. 55.2 rad/s^2 d. 35.2 rad/s^2

Application of the Principle of Conservation of Angular Momentum

A student on a piano stool rotates freely with an angular speed of 3.16 rev/s. The student holds a 1.50 kg mass in each outstretched arm, 0.794 m from the axis of rotation. The combined moment of inertia of the student and the stool, ignoring the two masses, is 5.45 kg*m2, a value that remains constant. As the student pulls his

Rotational axes and maximum stresses

1. Two solid aluminum shafts (G = 3.7x106 psi) are connected by the gears shown. Ends B and D are fixed. What is the angle through which end C rotates? 2. For the beam of the cross section shown, determine the location of the neutral axis from the bottom of the beam. 3. For the beam of question 8, determine the value o

Three problems on torque

1. At the local playground, a 16 kg child sits on the end of a horizontal teeter-totter, 1.5m from the pivot point. On the other side of the pivot an adult pushes straight down on the teeter-totter with a force of 95 N. In which direction does the teeter-totter rotate if the adult applies the force of a distance (a) 3.0 m, (b) 2

Rotational Dynamics

A jet transport has a weight of 1.00x10^6 N and is at rest on the runway. The two rear wheels are 15m behind the front wheel, and the plane's center of gravity is 12.6m behind the front wheel. Determine the normal force exerted by the ground on the front wheel and each of the two rear wheels.

Rotational Dynamics

Please help with the following problem. By means of a rope whose mass is negligible, two blocks are suspended over a pulley, as the drawing shows. The pulley can be treated as a uniform solid cylindrical disk. The downward acceleration of the 44.0-kg block is observed to be exactly one-half the acceleration due to gravity. N

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?