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ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
ASSIGNMENT 1
Question 1
A projectile is fired from the edge of a 150-m cliff with an initial velocity of 180 m/s at an
angle of 30°with the horizontal. Neglecting air resistance, find (a) the horizontal distance
from the gun to the point where the projectile strikes the ground, (b) the greatest elevation
above the ground reached by the projectile.
Figure 1
Question 2
A boy throws a ball at 0 in the air with a speed v0 at an angle Ө1. If he then throws another
ball with the same speed v0 at an angle Ө2 < Ө1, determine the time between the throws so
that the balls collide in mid air at B.
Figure 2
ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
Question 3
The man at A wishes to throw two darts at the target at B so that they arrive at the same time.
If each dart is thrown with a speed of 10 m/s, determine the angles ӨC and ӨD at which they
should be thrown and the time between each throw. Note that the first dart must be thrown at
ӨC (˃ӨD), then the second dart is thrown at ӨD.
Figure 3
Question 4
The tangential acceleration of the centrifuge cab is given by at = 0.5t m/s2 where t is in
seconds and at is in m/s2. If the centrifuge starts from rest, after 10 seconds;
(a)
Determine the tangential velocity of the cab
(b)
Determine the normal acceleration of the cab
(c)
Determine the total acceleration magnitude of the cab
Figure 4