Mechanics | Relativity Answers

A particle initially located at the origin has an acceleration of-2.00j m/s2 and an initial velocity of7.00i m/s (a) Find the vector position of the particle at any time t (where t is measured in seconds) t2 j) m (b) Find the velocity of the particle at any time t tj) m/s (c) Find the coordinates of the particle at t 4.00 s (d) Find the speed of the particle at t 4.00 s m/s

Find the resultant R of the following forces all acting on the same point in the given directions: 30lb northeast; 70 lb to the south; and 50 lb 20o north of west.

A jet of water, discharged from a nozzle, hits a screen 6 m away at a height of 4 m above
the centre of a nozzle. When the screen is moved 4 m further away, the jet hits it again at
the same point. Assuming the curve described by the jet to be parabolic, find the angle at
which the jet is projected. (Ans. 46° 51')

A stone is dropped from the top of a cliff 120 metres high. After one second, another stone is thrown
down and strikes the first stone when it has just reached the foot of the cliff. Find the velocity with
which the second stone was thrown.

A stone is dropped from the top of a cliff 120 metres high. After one second, another stone is thrown
down and strikes the first stone when it has just reached the foot of the cliff. Find the velocity with
which the second stone was thrown

A jet of water, discharged from a nozzle, hits a screen 6 m away at a height of 4 m above
the centre of a nozzle. When the screen is moved 4 m further away, the jet hits it again at
the same point. Assuming the curve described by the jet to be parabolic, find the angle at
which the jet is projected. (Ans. 46° 51')

(1.) Alex (mA = 66 kg; initially at x = 0) and Chris (mC = 58 kg) sit at opposite ends of a motionless boat (mb = 77 kg) whose length, L, is 1.7 m. Chris gets up and moves to Alex’s end of the boat. Assume the water offers no resistance to the motion of the boat.
(a.) If we make a system consisting of the two people + the boat + the Earth and assure ΣFext = 0, what is the change in this system’s momentum prior to and after Chris changing position? (2 pts) (b.) Given the coordinate system in the Figure, find the center-of-mass of this system, xCM, before Chris moves. You can assume the boat is symmetric and of uniform density. (7 pts)
(c.) Find the center-of-mass of this system, x′CM, after Chris moves, as a function of d, the distance the boat moves in the water. (7 pts)
(d.) Find d. (4 pts)

Explain why the mass of an object remains the same both on earth and on the moon,
but the same cannot be said about the weight of an object.

Three boxes are stacked on top of each other. The top box weighs 5 kg, the middle 20 kg and the bottom box weighs 50 kg.
Draw out all the forces acting on the middle box
Determine the magnitude of the forces