1. A truck is travelling at a speed of 60 km/h such that its wheels are rolling
ID: 1793174 • Letter: 1
Question
1. A truck is travelling at a speed of 60 km/h such that its wheels are rolling perfectly without slippage. What is the speed, in m/s, of a point on top of the wheel?
zero
11.9 m/s
23.6 m/s
33.3 m/s
2. The rotational kinetic energy of a hollow sphere of radius 40 cm and mass 1 kg is 0.48 J. With what angular speed is it rotating?
3. A 4 m long, thin, cylindrical rod of mass 3 kg is rotating with a rotational velocity of 6 rad/s about an axis at one of its ends and perpendicular to its central axis. What is its angular momentum?
96 kg m2/s
102 kg m2/s
115 kg m2/s
134 kg m2/s
zero
11.9 m/s
23.6 m/s
33.3 m/s
Explanation / Answer
1] Speed at top = v+wr = 2v = 2*60*5/18 m/s = 33.3 m/s answer
2] We know KE = 0.5 i w^2
0.48 = 0.5*2/3*1*0.4^2 w^2
w = sqrt(0.48/(0.5*2/3*1*0.4^2)) = 3 rad/s answer
3] Angular momentum = iw = 3*4^2/3*6 = 96 kgm/s answer
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