Mechanics | Relativity Answers

a sttel wire of diameter 1mm can supporta tension of 0.2kn. a cable to support a tension of 20kn should have a diameterv of what order of magnitude

A plane is flying with a constant speed along a straight line at an angle of 30
with the horizontal. The weight of the plane is 100000 N and its engine provides
a thrust of 120000 N in the direction of flight. Two additional forces are exerted
on the plane: the lift force perpendicular to the plane’s wings, and the force due
to air resistance opposite to the direction of motion. Draw the free-body diagram
showing all forces on the plane. Determine the lift force and the force due to air
resistance

. A child of mass 30 kg skates down from the top of a ramp having a constant slope of
15. The child’s speed increases from 1 1.5ms to 1 3.0ms as she reaches the
bottom of the ramp. A force of kinetic friction of magnitude 50 N opposes her
motion. Draw the appropriate force diagram and determine the length of the ramp.
Take 10ms .

A solid sphere of mass 100 kg and radius 10 m moving in a space becomes a circular disc of radius 20 m in one hour. Then the rate of change of moment of inertia in the process is

a train moving with constant acceleration travels 24ft. during the 10th sec of its motion and 18 ft during the 12th sec of its motion. find its initial velocity and its constant acceleration

A rod of length L is pivoted from its top end about an axis perpendicular to the rod to form a physical pendulum. The rod has a non-uniform linear mass density λ(y) = A y2 where y is the distance from the pivoted top end and A is a positive constant. (In practice, this could be realized approximately by having the rod actually be conical in shape with a small cone angle.)
(a) What are the (SI) units of A?
(b) Find the period T of the rod’s oscillations (for small oscillations) in terms of L and perhaps, constants (e.g., π, ⅓, g, ...).

A physical pendulum consists of a uniform solid disk of radius R supported in a vertical plane by a pivot located a distance d from the center of the disk. The disk is displaced a small angle and released.
a) Starting with T=2pi(I/mgd)^(1/2) , derive an expression for the period of the resulting simple harmonic motion in terms of the quantities given in the problem and, perhaps, constants (e.g., π, ⅓, g, ...).
b) Find an expression for the distance d that results in the shortest period and use that to write a formula for this shortest periodT. Write this result in terms of the quantities given in the problem and, perhaps, constants (e.g., π, ⅓, g, ...).
c) Calculate a numerical value for the shortest period if R = 2.35 cm.

Two identical thin rods of length L (and equal mass) are joined at right angles to form an L-shaped object. This object is balanced in a vertical plane on top of a sharp edge. The L-shaped object oscillates as a physical pendulum when it is slightly deflected (small angle). Starting with T=2pi(I/mgd)^(1/2), derive an expression for the frequency of the oscillation. Write the result in terms of thequantities given in the problem and, perhaps, constants (e.g., π, ⅓, g, ...).

the net force on a 12 kg cart is 3.2 N back ward . Ignoring friction , what is the acceleration of the car

A 4N soccer ball sits motionless on a field. A player's foot exerts a force of 6 N on the ball for a distance of 0.12 m, and the ball rolls a distance of 12 meters. How much kineitic energy does the ball gain from the player