explain for a rating a uniform ladder is resting against a wall as shown. Both t
ID: 2123317 • Letter: E
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explain for a rating
a uniform ladder is resting against a wall as shown. Both the wall and the floor are frictionless, so the forces exerted by the wall and the floor on the ladder are both normal forces. The ladder is held in place by a taut rope which is tied between points B and C. If the angle theta = 30. 0 theta, and the tension in the rope is 40. 0 N, then the eight of the ladder is: 40 N 139 N 80 N 69 N 184 N 92 N Suppose that the pendulum bobs in the figure are made of soft clay so that they stick together after impact. The mass of bob a is half that of bob B. The velocity of bob a just prior to impact is directed to the right and symbolized as nu a Bob B is initially at rest (nu B = 0). What is the ratio of the kinetic energy of the combined bobs, just after impact, to the kinetic energy of bob a alone just before impact?1 1/2 2 1/3 3 ¼ 2/3Explanation / Answer
6) B)139 N
let W is the weight of the ladder.
net force in x-direction is zero.
let Nw is the Normal force exerted by wall
Nw - 40 = 0
Nw = 40 N
net torque acting on the ladder is zero
Nw*L*sin(60) - W*(L/2)*sin(30) = 0
W*(L/2)*sin(30) = Nw*L*sin(60)
W = 2*Nw*sin(60)/sin(30) = 138.56 N = 139 N
7) D) 1/3
initial momentum = ma*Va
mb = 2*ma
let V is the final velocity
final momentum = (ma+mb)*V = 3*ma*v
here, momentum is conserved = maVa = 3*ma*V
final velocity V = Va / 3
initial KE = 0.5 m Va^2
final kinetic energy = 0.5 (ma+2ma)(Va/3)^2
ratio = 0.5 (ma+2ma)(Va/3)^2 / 0.5*ma*Va^2 = 1/3
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