ASSIGNMENT 7
1.Knight 7.002. [455030]Show Details
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Figure Ex7.2 shows the angular-velocity-versus-time graph for a particle moving in a circle.
Figure Ex7.2
How many revolutions does the object make during the first 4 s?
rev
2.Knight 7.016. [370383]Show Details
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A 28 g ball rolls around a 40 cm diameter L-shaped track, shown in Figure Ex7.16, at 60 rpm. What is the magnitude of the net force that the track exerts on the ball? Rolling friction can be neglected.
N
Figure Ex7.16
3.Knight 7.026. [518997]Show Details
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A computer disk is 8.0 cm in diameter. A reference dot on the edge of the disk is initially located at = +45°. The disk accelerates steadily for second, reaching 1600 rpm, then coasts at steady angular velocity for another second. What are the location and speed of the reference dot at t = 1 s?
location / °speed / m/s
4.Knight 7.051. [370388]Show Details
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A 100 g ball on a 60 cm long string is swung in a vertical circle about a point 200 cm above the floor. The tension in the string when the ball is at the very bottom of the circle is 6.0 N. A very sharp knife is suddenly inserted, as shown in Figure P7.51, to cut the string directly below the point of support. Where does the ball hit the floor? (Measure from the point where the string was cut and consider right to be the positive direction.)
m
Figure P7.51
5.Knight 7.055. [455070]Show Details
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A 600 g steel block rotates on a steel table (μk = 0.6) while attached to a 0.8 m long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 4.8 N perpendicular to the tube. The maximum tension the tube can withstand without breaking is 50 N. If the block starts from rest, how many revolutions does it make before the tube breaks?
rev
Figure P7.55
6.Knight 7.052. [455018]Show Details
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A 100 g ball on a 60 cm long string is swung in a vertical circle about a point 200 cm above the floor. The string suddenly breaks when it is parallel to the ground and the ball is moving upward. The ball reaches a height of 600 cm above the floor. What was the tension in the string an instant before it broke?
N
7.Knight 7.061. [370379]Show Details
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Two wires are tied to the 340 g sphere shown in Figure CP7.61. The sphere revolves in a horizontal circle at a constant speed of 8.0 m/s. What is the tension in each of the wires?
T1 = N (top wire)
T2 = N (bottom wire)
Figure CP7.61
8.Knight 7.044. [455060]Show Details
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A car drives over the top of a hill that has a radius of 34 m. What maximum speed can the car have without flying off the road at the top of the hill?
m/s
9.Knight 7.040. [370380]Show Details
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A small ball rolls around a horizontal circle at height y inside the cone shown in Figure P7.40. Find an expression of the ball's speed in terms of y and g only.
v =
Figure P7.40
10.Knight 7.039. [455037]Show Details
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A conical pendulum is formed by attaching a 410 g ball to a 1.0 m long string, then allowing the mass to move in a horizontal circle of radius 26 cm. Figure P7.39 shows that the string traces out the surface of a cone, hence the name.
Figure P7.39
(a) What is the tension in the string?
N
(b) What is the ball's angular velocity, in rpm?
rpm