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Unit: SEP101 Engineering Physics Date: Trimester 1, 2011

PART A MULTIPLE CHOICE

Question Answers Question Answers Question Answers1 C 11 A 21 D2 D 12 C 22 C3 C 13 C 23 B4 E 14 E 24 D5 D 15 B 25 C6 A 16 A 26 A7 C 17 B 27 B

8 B 18 B 28 A9 D 19 D 29 D

10 B 20 A 30 D

PART B

QUESTION B 1.1 A 3.5 kg block is pushed along a horizontal floor by a force of magnitude 15 N at an anglewith the horizontal. The coefficient of kinetic friction between the block and the floor is 0.25. Calculatethe magnitudes of

(a) The frictional force on the block from the floor and

(b) The blocks acceleration

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b) In the figure below block 1 (mass 1.6 kg) slides into block 2 (mass 2.4 kg), along a frictionlesssurface. The collision is elastic . The directions of three velocities before and after the collision areindicated; the corresponding speeds are before collision u 1= 5.5 m/s, u2= 2.5 m/s, and after the collisionv2 = 4.9 m/s. What is v 1, the velocity of block 1 after the collision?

U1 u 2

2 1

v V21 2

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QUESTION B 1.3

For the figure below, determine the location yc of the centroidal axis xc of the beam's cross-sectionalarea. Neglect the size of the corner welds at A and B for the calculation.

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QUESTION B 2.1

In the figure shown below a uniform beam, of length L and mass m = 1.8 kg, is at rest on two scales. Auniform block, with mass M = 2.7 kg, is at rest on the beam, with its centre a distance L/4 from the beam'sleft end. What do the scales read?

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QUESTION B 2.2

The U-tube in the figure below contains two liquids in static equilibrium: Water of densityw (= 998 kg/m

3) is in the right arm, and oil of unknown density x is in the left. Measurement gives l =135 mm and d = 12.3 mm. What is the density of the oil?

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