Mechanics | Relativity Answers

Find the tension in the horizontal part of the supporting cable, and the compression in the boom, elevated to 25.0° , of the crane that lifts a 8900. N load.

A rigid plank 5.00 m long has mass 30.0 kg and supports a 75.0 kg block 2.00 m from the left end. How much force is needed to support each end of the plank?

A body of mass 3kg and volume 4 * 0.0004 m is hung from a balance graduated in Newton’s what is the reading balance when the body is

A bottle dropped from a balloon reaches the ground in 20.0 s. Determine the height of the balloon if a) it was at rest in the air and b) it was ascending with a speed of 50.0 m/s when the bottle was dropped

b) Show that there is a time dilation for a clock that moves at a relativistic velocity v relative to an

observer who is on the ground taking readings.

A Ferris wheel of radius 12m is turning about a horizontal axis through its center, such that the linear speed of a passenger on the rim is constant and equal to 9m/s.

a) What are the magnitude and direction of the acceleration of the passenger as he passes

through the lowest point in his circular motion?

A model of a helicopter rotor has four blades, each 3.40 m

long from the central shaft to the blade tip. The model is rotated in a wind tunnel at 550 rev/min (a) What is the linear speed of the blade tip, in (b) What is the radial acceleration of the blade tip expressed as a multiple of the acceleration of gravity, g?

A batter hits a baseball so that it leaves the bat with an initial speed 37.0 an initial angle 53.1o, at a location. Find

a) the position of the ball at t = 2.00 s.

b) the magnitude and direction of its velocity,

when t = 2.00 s.

c) the time when the ball reaches the highest point of its flight. d) its maximum height, h.

e) its horizontal range, 𝑅.

You are operating a remote-controlled model car on a vacant tennis court. Your position is the origin of coordinates, and the surface of the court lies in the 𝑥𝑦-plane. The car, which we represent as a point, has x- and y- coordinates that vary with time according to

 a) Find the car’s coordinates and its distance from you at time t = 2.0 s.

b) Find the car’s displacement and average velocity vectors during the interval from

t = 0 s to t = 2.0 s.

c) Find the components of the average acceleration in the interval from t = 0 s to t =

2.0 s.

In a 300-m race, runner A starts from rests and accelerates at 1.6m/s2 for the first 30 m and then runs at a constant speed. Runner B starts from rests and accelerates at 2.0m/s2 for the first 30m and then runs at a constant speed. Runner A begins running as soon as the race begins but B firsts takes a nap to rest up. What is the longest nap that B can take and still not to lose the race?