Download Function of Time - Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! Physics 21 Spring 2012 Test 1 (4 pages)
name: Soluhon February 8, 2012 Total Score: | 20) /120__
Your solutions must begin with any of the following Starting Equations (or their y-cquivalent):
1 2 7
X= Xo t Voxt +5 a,t? Ve = Vox + Ayt Vy" = Vox? + 2 ay(x — Xp)
LA = may fs SUsN fie = KN
Di (5) The x-component of an object’s position as a function of time t is given by x(t) = bt - ct'+d where b, ¢
and d are positive constants. Which of the following is true about the object?
A) Its acceleration is constant. B) At time 0 it moves in the negative x-direction.
C) Its x-component of velocity is time dependent and always positive. Write 3¢
D) It does not always move in the same direction.
Av2) ‘The #hotion of an object is described by the vs-t- 2m/s
diagram at the right. Which of the following is false?
A) The object is at rest at A.
B) The object is moving to the right at B. - 2m/s
C) The object is speeding up at C.
D) The object is slowing down at D.
AB (5) A fisherman yanks a fish vertically out of the water with an upward acceleration of 5 m/s’, using a
very light fishing line that has a breaking strength of 30N. ‘The fisherman unfortunately loses the fish as the line
snaps. You can infer that the mass of the fish must have been more than 4 T + Ma = Ma
A) 2kg B) 3kg C) 6kg D)30N
JN :
-—D at ¢
b 4. (5) A box is at rest on a rough inclined plane. The reaction force to the weight force on the book is
A) the vertical component of the normal force. B) the force of gravity exerted by the book on the Earth.
C) the force exerted by the book on the incline. 1D) the force of static friction.
a
B 5) A monkey is pushing a box of bananas of mass m with a force P up a rough incline that makes an
angle o with the horizontal. ‘The force is directed parallel to the incline and the coefficient of kinetic friction
between box and incline is jt. The magnitude of the foree exerted by the box on the monkey equals
A) F- pumg cos a B)F C) F- umg sin a D) F-g sin uw
A 6. (3) A ball is twirled at the end of a string in a vertical circle at constant speed. At what position does
the tension in the string have the largest magnitude?
A) at the bottom B) at the top
C) when the string is horizontal D) the tension is the same everywhere.
/30 points for this page
Physics 21 Test 1 Spring 2012 1
7) (30) In a lecture demonstration, the instructor
aims a blow gun directly al Barney, a stuffed
purple dinosaur, who is suspended from the
ceiling at a vertical height // above the muzvle of
the blow gun, a horizontal distance D away. At
the instant she launches a dart with speed vo,
Barney is released from rest.
a) In the diagram, add all information necessary
to solve part b) below. Remember, any symbol
you use must be defined in the diagram.
b) Derive an expression, in terms of system parameters. for the dart’s vertical position when the dart has
covered the horizontal distance D. 9
¢) Derive an expression, in terms of system parameters,
has the covered horizontal distance D.
30 paints for this page
Physics 21 Test 1 Spring 2012 2
