Mechanics | Relativity Answers

Calculate the tensile force required to produce an elongation of 0.1 percent in a wire of radius 0.5
mm. (The Young’s modulus of the material of the wire is 1.0 × 1011 N m–2)

Two forces with magnitudes of 131 and 52 newtons act on point with a resultant force of 100
newtons. Find the angle, in radians, between the forces.

Prove that kinetic energy of a gas molecule depends only on its absolute temperature.

A = 3i + 4j
JG and B =
JG i – j, are two vectors in x, y plane. Find the magnitude of the sum of these
two vectors

A ball is thrown with a speed of 20 m s–1 in a direction 30° above the horizontal. Calculate (i) the
maximum height attained by the ball and (iii) the time taken by the ball to return to the same level
(Take g = 10 m s–2).

A body starts from rest in a straight line under a force causing a constant acceleration of 2 m s–2.
After 10s the force is removed and the body comes to rest in 20 seconds. Find the distance travelled by the body in the last 20s.

Julia can run a mile race in 4.25 min. Jasmine requires 4.55 min to run this distance. If they start out together and maintain their normal speeds, how far apart will they be at the finish of the race?

Jed was driving his car at 40 km/h on a subdivision where the speed limit is 20 km/h. He was spotted by an officer in a motorcycle, who accelerates in pursuit. By the time Jed sees the officer's motorcycle it as travelling at 60 km/h. What is the officer's motorcycle's velocity relative to Jed's car?

A school bus heading east through a small town accelerates as it passes the sign post at s = 0. Marking the city limits. Its acceleration is constant 5 m/s^2 at time 0; it is 5 m east of the (+) sign post and has a velocity of 3 m/s (a) Find his position and velocity at 2 seconds. (B) where is it when its velocity is 5 m/s.

Suppose that the starship Enterprise from Star Trek has a mass of 8.0 × 107 kg, about the same as the Queen Elizabeth 2. Suppose that it was moving at half the speed of light. Read its G off of the graph in figure l on p. 76, and use this to compute its energy. Compare with the total energy content of the world’s nuclear arsenals, which is about 1021 J.