MCS702S
Mechanics
January 2024
1. (a) The position of a particle as it moves along a y au-xiiss given by
y(t)=2sin:t
with t in seconds and y in centimeter
1. What is the average velocity and average acceleration of the particle between
t = 0 and t = 2s?
(6)
ii. What is the instantaneous velocity and instantaneous acceleration of the par-
ticle at t = Os,ls and 2s?
(7)
(b) Newton sets out from his home to deliver flyers for her yard sale, traveling due east
along his street lined with houses. At 0.5 km and 9 minutes later he runs out of
flyers and has to retrace his steps back to his house to get more. This takes an
additional 9 minutes. After picking up more flyers, he sets out again on the same
path, continuing where he left off, and ends up 1.0 km from his house. This third leg
of hiss trip takes 15 minutes. At this point he turns back toward his house,heading
west. After 1.75 km and 25 minutes he stops to rest.
i. What is Newtons total displacement to the point where she stops torest?
(2)
ii. What is the total distance traveled?
(2)
2. (a) An uncooperative cow is leaving the barn as you try harder and harder to push her
back in. In coordinates with the originat the barn door, the cow walks from x = 0
to x = 6.9m as you apply a force with x-component
F.x= -(20N + (3N/m)x.
How much work does the force you apply do on the cow during this displacement?
(6)
(b) A net force along the x-axis that has x-component Fx = -12N + (0.3N/m 4 )x 2 is
applied to a 5 kg object that is initially at the origin and moving in the -x-direction
with a speed of 6m/ s. What is the speed of the object when it reaches the point
x=5m?
(~
3. (a) Two football players, one weighing 95 kg and moving at 3.75 m/s, and the other wei-
ghing 111 kg and moving at 4.10 m/s, approach each other along a linear trajectory.
They eventually collide head-on and become entangled.
i. What is their velocity immediately after the collision?
(5)
ii. What are the initial and final kinetic energies of the system?
(5)
(b) Two cars have a collision at a perpendicular intersection. In a top-down view of this
intersection, the first car, weighing 950 kg, is approaching from the left at a speed
of 16 m/s. The second car, with a mass of 1300 kg, is approaching from below at
a speed of 21 m/s. After the collision, they merge together. Find the speed and
direction of the vehicles just after the collision. Assume there are no external forces (8)
4. (a) A force F = (2i + 9j + 5.3k)N acts on 2.9kg object that moves in time interval
2.10s from an initial position
(-4.li + 3.3j + 5.4k)m.
r1 =
(2.7i -
2.9j + 5.5k)m
to
a final position
r2
=
2