Download Midterm Examination

THE INTERNATIONAL UNIVERSITY (IU)
VIETNAM NATIONAL UNIVERSITY - HCMC
ASSIGNMENT-ANSWER
SUBJECT: PHYSICS 1
GROUP: 8-10 STUDENTS
(To submit the 13th May 2016)
Student Name:_______________________Student ID:___________________
1/ (20 pts) A body of mass 1 kg and a body of mass 2 kg collide on a smooth horizontal surface. Before the
collision the 1 kg body has velocity 3 m/s directed due north and the 2 kg body has velocity 5 m/s directed
northeast (i.e. 45o east of due north). The two bodies stick together, forming a body of mass 3 kg.
a/ Find the magnitude and direction of the velocity of the 3 kg body.
b/ Is this collision elastic? Explain.
2/ (20 pts) A 2.50-kg textbook is forced against a horizontal spring of negligible mass and force constant 250 N/m,
compressing the spring a distance of 0.250 m. When released, the textbook slides on a horizontal tabletop with
coefficient of kinetic friction k = 0.30. Use the work-energy theorem to find how far the textbook moves from its
initial position before coming to rest.
8.00 kg
3/ (20 pts) (20 pts) Consider the system shown in the Fig. 1. The rope and pulley
have negligible mass, and the pulley is frictionless. Initially the 6.00-kg block is
moving downward and the 8.00-kg block is moving to the right, both with a
6.00 kg
speed of 0.900 m/s. The blocks come to rest after moving 2.00 m. Calculate the
coefficient of kinetic friction between the 8.00-kg block and the tabletop.
Fig. 1
4/ (20 pts) An object moving in the xy-plane is acted on by a conservative force
 1
1 
described by the potential-energy function U ( x, y)    2  2  , where  is a positive constant. Derive an
y 
x
expression for the force expressed in terms of the unit vectors i and j of the xy-plane.
5/ (20 pts) A ball of mass 0.25 kg glances of a wall as shown in the
diagram. The ball approaches at 15 m/s at θ = 30° and leaves at12 m/s
at φ = 20°. The collision lasts for 15 milliseconds.
(a) What is the impulse experienced by the ball?
(b) What is the average force acting on the ball?
The end