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ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
TUTORIAL 1
QUESTION 1
1. The jet-powered boat starts from rest at s=0 and travels along a straight line with the
speed described by the graph. Construct the s-t and a-t graph for the time interval 0 ≤ t ≤
50s.
Figure 1
ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
QUESTION 2
The boy at A attempts to throw a ball over the roof of a barn with an initial speed of vA = 15
m/s. Determine the angle ϴA at which the ball must be thrown so that it reaches its maximum
height at C. Also, find the distance d where the boy should stand to make the throw.
ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
QUESTION 3
When a rocket fired from A at x=0 and it begins to travel along parabolic path defined by the
parametric equation y 2  240 x , where the coordinate are measured in metres. If the
component of acceleration is a x  5t 2 m/s, where t is in seconds, determine the magnitude of
the rocket’s velocity and acceleration when t=10 s.
Figure 3
ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
QUESTION 4
When the roller coaster is at B, it has a speed of 25 m/s, which is increasing at at  3 m/s2.
Determine the magnitude of the acceleration of the roller coaster at this instant and the
direction angle it makes with the x-axis.
Figure 4
ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
QUESTION 5
The two blocks A and B having mass of 10 kg and 30 kg respectively, that shown in Figure 5
are originally at rest. Neglect the masses of the pulleys and the effect of friction in the pulleys.
When the blocks are released, determine:
(a) Acceleration of each block.
(b) Tension of the cable.
Figure 5
ENT142/3 - ENGINEERING DYNAMICS (SEMESTER 2 - 2014/15 ACADEMIC SESSION)
QUESTION 6
The crate has a mass of 80 kg and is being towed by a chain which is always directed at 20°
from the horizontal as shown in Figure 6. Given the coefficient of static friction is the
coefficient of kinetic friction is and the towing force is P = (90t2) N, where t is in seconds.
(a) Does the crate moves at t = 2 s? Prove your answer with calculation.
(b) Determine the crate's acceleration in t = 3 s.
Figure 6