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Unformatted text preview: Dawson college Physics NYA Final Examination Thursday, May 19, 2005
9:30 am. to 12:30 pm.
Teachers: N.Ahmed, M. Chaubey, G. Saxena, P. Simpson INSTRUCTIONS : 1. Do (a) any 8 of the 10 problems in Part1 (10 marks each) and
(b) any 10 of the 14 conceptual questions in Part II (2 points each) 2. You may detach the formula sheet from the examination paper.
3. . The time allotted for the examination is three hours. 4. Show all of your work. 5. Write your name and your teacher’s name on the front of each booklet that you
hand in.
5. If you use more than one booklet write the total number of booklets you used on the ﬁrst booklet and slip the other booklets inside of it. #1. Part I: Long Answer Problems
Solve any 8 of the 10 problems in Part I ' A CARE package 13 dropped from a helicopter hovering 320 to above the ground. It falls freely for 4 s and then a parachute opens, decelerating it at 3 111/32. How fast 15 it
moving just before it hits the ground?  #2. The tortoise is moving along at a steady speed of 2 111’s 10 m from the ﬁnish line of the famous race. The hare= just waking up from a refreshing nap, is standing 24 in behind the tortoise. The hare immediately begins to accelerate at 4 rn/s2 towards the .
ﬁnish line. When he catches up to the tortoise #3. a) How much time has elapsed since he started to accelerate? b) How far has the tortoise moved? (Who wins the race?) (Assume that the
tortoise keeps moving at the same rate until the hare catches him.)
0) How fast is the hare moving? EMS” 160 N, 36° North of West
= 250N, 20° East of South
C = IOON, East ﬁnd R = A‘i'ﬁ‘lC , using the component method. Find the magnitude and
direction of ii. a) Given the three vectors A
13 b) If a force 13 = 20:” —3oj'—5012 N acts on a particle ofrnass 0.150 kg that is
moving at a velocity of 17 = 3? — 6} + 2]; mfs i) What is the instantaneous power being delivered to the mass?
ii) What is the angle between the force and. the velocity? c) If a force F = Si —7} —912 N is applied to an object at a point that is Fm  —i + 3}: + 212m from the axis of rotation of the object, ﬁnd the torque that the force exerts about that axis. (Assume that the axis passes through the origin and IS
perpendicular to the plane deﬁned by the force and radius vectors.) 02 W  #4. A 1 kg block, tied to the wall with a rope, rests on top of a 2 kg block. The lower
block is pulled to the right with a horizontal force of 20N. The coefﬁcient of kinetic
 ﬁiction between the blocks and betWeen the lower block and the ﬂoor is pk = 0.4. a) Draw a free body diagram for each block. ‘ b) Find the tension in the rope holding the upper block.
c) Find the acceleration of the lower block. #5. A ball is thrown towards a cliff of height h, with a speed of 25 mfs at an angle of
53° above horizontal. It lands on the edge of the cliff 3 seconds later. a) How high is the cliff? b) How far from the base of the chff was the ball when it was thrown?
c) What IS the maximum height that the ball reached? d) What IS the hall’s velocity just before it hits the edge of the cliff? Give its
magnitude and direction. #6. A 1500 kg car moving on a ﬂat horizontal road negotiates a curve of radius 35.0
metres. The coefﬁcient of static friction betweenlthe tires and dry road is 0.562. a) Find the maximum speed at which the car can successfully negotiate the curve,
in km/hr.
b) On an icy day in winter, thecoefﬁcient of static friction between the tires and the road is reduced to 'A the value it has when the road is dry. What is the
maximum speed at which the car can successfully negotiate the curve now? gas/M #7. A 1000 kg car, traveling East at 30 m/s, collides with a 3000 kg truck traveling , North. Aﬂer the collision, the vehicles stick together as one lump of wreckage moving in
the direction 55" North of East. 21) Find the speed of the truck before the collision: ‘ b) What percentage of the total initial kinetic energy of the two vehicles was lost
during the collision? ' #3. A spring with constant 2500 sum is sandwiched betWBen a 2 kg block and a 3 kg
block on a frictionless table. The blocks are pushed together to compress the spring by 15 cm, then released. (See the ﬁgure below.) Find the velocity of each block after they have
separated from the spring. .2 WV #9. A 500 g box slides down a 2.5 m high frictionless hill, starting from rest At the bottom of the hill, it crosses a rough (pk— — 0. 25) horizontal patch of ﬂoor 2.0 m long. Finally it hits a horizontal spring (k= 700 me) whose other end IS anchored against a 
wall. The ground under the spring is frictionless. , $003. <— QIOrm “—> '— a) How far is the Spring compressed the ﬁrst time the mass hits it? b) How many trips (including the ﬁrst one) will the boic make across the rough
surface before coming to rest? #10. The four masses, shown below, are connected by massless rigid rods. 5
ﬁlo200 C 0300
0 hj 9 ‘3 09.an a) Find the coordjnates of the centre of mass of this assembly. b) Find the moment of inertia about an axis perpendicular to the plane of the
masses and passing through mass A. (Le. the z—axis) c) Ifthis assembly of masses is rotating about thenaxis at 30 rpm, ﬁnd the net
torque that will bring it to rest in 10.0 seconds. alt/*3) Part II: Conceptual Questions
Answer any 10 of the 14 questions in Part II. WRITE THE ANSWERS TO ALL UESTIONS IN 'THE EXAM BOOKLET". _ _. _.’ 2, ..2 —.2 .. _ .
#1. HA+B=Cand [Al +lB =C ,what does AiB equal? #2. Sketch the displacementtime that corresponds to the velocitytime graph below.
Assume x=0 at t=0. t= . '
_ Ill'l "“n “L . it: “digﬁ E Til. . 51? L.“ III 215: (“1.4.7  — E: #3. A car is moving at a constant velocity of 25 m/s East along a snaight level
highway. One may conclude that ‘ A. There is exactly one force acting on the car. B. There is a non—zero net force acting on the car in the eastward direction.
C. The net force acting on the car is zero. D. There must he no forces at all acting on the car. #4. Consider a small bug sitting on a rotating ceiling fan. (It’s his version of going to
La Ronde.) Which of the variables describing his motion change with time? . only his position only his velocity only his acceleration . only his position and velocity ‘
his position, velocity and acceleration wuow> . MW ' #5. A truck loaded with sand accelerates along a highway. Ifthe driving forde of the truck remains constant, what happens to the truck’s acceleration if the sand leaks out of it
at a constant rate? #6. A man drives at constant speed over a hill, through a valley, and onto a ﬂat section _
of road. At which point will his apparent weight be the greatest— A or B or C? (i.e. Ifhe
was sitting on a scale,at which point would the reading on the scale be the greatest?) 6 #7. A rocket is traveling due East when it is suddenly hit by a big rock traveling due
North. In which case would the direction of the rocket change more: A. The rock sticks to the rocket.
B. The rock bounces back, moving due South after the collision. #8. The mass of object A is twice the mass of object 13. They have equal kinetic
energies. What is the ratio of the momentum of mass A to the momentum of mass B?  #9. A boy standing on the edge of a cliff throws three identical rocks X, Y and Z with
the same speed. Rock X isthrown straight up; Rock Y straight down and Rock Z horizontally. Assuming that the ground at the base of the cliff is ﬂat, which rock hits the
ground at the highest speed? Rook X Rock Y Rock Z . Rocks X and Y hit with the same speed, faster than Rock Z.
All three rocks hit the ground with the same speed. meow? #10. Rami and Jamie throw identical balls upwards. Rami throws his ball with twice the
speed that Jamie does. The maximum height of Rami’s ball will be: A. The same'a‘s Jamie's ball B. Twice that of Jamie’s ball C. Four times that of Jamie’s ball
D. Eight times that of Jamie’s ball #11. The graph below shows the potential energy of a particle due to the force exerted on
it by another particle as a function of the distance between them. The force will be zero at
which of the following points? we A. X D.XandY
B. Y  E.YandZ
c z nxmz #12. All points on a rigid body rotating with uniform angular velocity have: A. the same angular velocity, and the same linear velocity.
B. the same angular velocity, but different linear velocities.
C. diﬁerent angular velocities, but the same linear velocity.
D. different angular velocities and different linear velocities. #13. A child of mass 20 kg sits 1.4 In to the left of the pivot point of a seesaw. Another
child of mass 35 kg sits 0.8 In to the right of the pivot point. Assuming the see—saw itself
is massless, the seesaw will ’Rue‘t‘ ﬂairFT £—— —5< —>
f'4w O'gq... A. rotate counterclockwise,
B. rotate clockwise.
C. will not rotate at all. #14. A 50 kg person is standing on the ﬂoor. Draw a free body diagram to show the two
forces acting on her. Are these forces an actionreaction pair? Explain. MW ...
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 Fall '09
 MS.SIMPSON

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