Unformatted text preview: /.) E102 MidTerm Practice Problems A girl rolls a ball up an incline and allows it to re—
turn to her. For the angle 9 and ball involved the ac—
celeration of the ball along the incline is constant at
0.25g, directed down the incline. If the ball is re
leased with a speed of 4 m/s, determine the distance
3 it moves up the incline before reversing its direc
tion and the total time 1 required for the ball to re
turn to the child‘s hand. Ans. s = 3.26 m, t = 3.26 s The car is traveling at a constant speed yo = 100
km/h on the level portion of the road. When the
6percent (tan 0 = 6/100) incline is encountered, the
driver does not change the throttle setting and con
sequently the car deoelerates at the constant rate 3
sin 8. Determine the speed of the car (a) 10 seconds
after passing pointA and (b) when 5 = 100 m. Ans. (a) v = 21.9 m/s, (b) u = 25.6 m/s 3l The coefficient of static friction between the ﬂatbed £7) The robot arm is elevating and extending simulta neously At a given instant, 9 = 30", H = 10 deg/s =
constant, I: 0.,5m l — 0.,2111/5 and l 03m/sz. Compute the magnitudes of the velocity v and ac
celeration a of the gripped part P. In addition, ex of the truck and the crate it carries is 0.30. Deter
mine the minimum stopping distance s which the
tiuck can have from a speed of 70 km/h with con
stant deceleration if the crate is not to slip forward.
Ans. s = 64.3 m press v and a in terms of the unit vectors i and j. * 0296 m/s, (1 = 0.345 m/s2 v = 0.064i + 0.289j m/s 3 = ~o.3zsi — 0.1086j m/s.2 The small spheres, which have the masses and ini
tial velocities shown in the ﬁgure, strike and be
come attached to the spiked ends of the rod, which
is freely pivoted at O and is initially at rest. Deter
mine the angular velocity m of the assembly after
impact. Neglect the mass of the rod. ans: 5v/3L Q l The three small spheres are weldedkto the light rigid frame which is rotating in a horizontal plane
about a vertical axis through 0 with an angular ve
locity 3‘ = 20 rad/s. Ifa couple Mo = 30 N m is ap
plied to the frame for 5 seconds compute the new angular velocity 8. .
Ans. 0' : 80.7 rad/s ...
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 Winter '08
 Eke

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