POKHARA UNIVERSITY
Level: Bachelor
Programme: BE
Semester – Spring
Course: Applied Mechanics II
Year
: 2010
Full Marks : 100
Pass Mark : 45
Time
: 3 hrs
Candidates are required to give their answers in their own words as far
as practicable.
The figures in the margin indicate full marks.
Attempt all the questions.
1.
a. A stone is thrown vertically upward from a point on a bridge 7
located 40 m above the water and that it strikes the water 4 sec
after release. Determine (a) speed with which the stone was
thrown upward (b) the speed with which the stone strikes the
water.
b. Car A and B are travelling in adjacent highway lanes and t = 0 8
have the positions and speed shown knowing that car A has a
constant acceleration of 0.6 m/s2 and that B has a constant
deceleration of 0.4 m/s2. Determine (a) when and where A will
overtake B, (b) the speed of each car at that time.
A
2.
B
The 3 kg collar was moving down the rod with a velocity of 3 m/s 15
when a force F was applied to the horizontal cable. Assuming a
coefficient of friction 0.2 between the collar and rod. Determine the
magnitude of force F if the collar stopped after moving 1 m more
down the rod.
1
F
300
3.
A spring is used to stop a 75 kg package which is moving down a 15
20° incline. The spring has a constant K = 25 kN/m, and is held by
cables so that it is initially compressed 100 mm. The velocity of the
package is 6 m/s. When it is 10 m from the spring and neglecting
friction, determine the maximum additional deformation of the
spring in bringing the package to rest. Assume μ =0.2.
6
m
/s
75
10
kg
m
Cable
20°
4.
A 240 kg space vehicle travelling with velocity VO = 500 k m/s 15
passes through the origin O at t = 0. Explosive charges then separate
the vehicle into three parts A, B and C, of mass 40 kg, 80 kg and 120
kg respectively. Knowing that at t = 3 s the positions of three parts
are, respectively, A (150, 150, 1350), B (375, 825, 2075) and
C (-300, -600, 1200), where the coordinates are expressed in meters,
that the velocity of C is VC = -100 i -200 j + 400k m/s, and that the y
component of the velocity of B is + 350 m/s. Determine the velocity
of part A.
5.
A 120 × 180 cm2 rectangle plate weighting 100 N is suspended from 15
two pins A and B. If pin B is suddenly removed, determine angular
2
acceleration of plate.
B
A
120 cm
180 cm
6.
7.
The pulleys shown has a mass moment of inertia of 20 kg m2 and is 15
initially at rest. The outside radius is 0.4 m and the inner radius is
0.2 m. Determine (a) the angular acceleration of each pulley, (b) the
angular velocity of each pulley after point A on the cord has moved
3 m.
Write short notes on any two:
a. Projectile
b. Newton’s Second law of motion
c. Translation
3
2×5