Question

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A rock is thrown horizontally from the top of a 10 m cliff with an initial horizontal velocity of 10 m/s. It has a Kinetic energy of 78 J when it in at a height of 3.0 m above the ground. If 20% of its initial mechanical energy is used in against the air friction, the mass of the rock is: 0.5 kg 1.0 kg 1.5 kg 2.0 kg None of the above The height, above the ground level of a 1.0 kg ball dropped from the top of a tall building is given by y(f) =120 - 10.01 - 3.2t. The percentage of the initial mechanical energy of the ball used against air friction in the first 4.00 s is approximately: 10% 25% 20% 15% None of the above A particle free to move in the x-y plane and initially at rest at (0.20 m. 0.40 m). moves under the influence of a force whose components are given by F_x(x) = (6.0 N/m)x and F_y(y) = 2.0 N + (2.5 N/m^2)y^2. If the mass of the particle is 0.050 kg. the magnitude of velocity (speed) at (2.2 m. 3.4 m) is: 12.4 m/s 18.6 m/s 29 m/s 39 m/s None of the above A metal gas storage tank explodes breaking into three pieces, two of equal mass and the third having twice the mass of each of the others. The two equal mass parts fly off 'at speeds of 21.0 m/s at an angle of I OOP between them. The speed (magnitude of velocity) of the heavier mass is: 11.5 m/s 13.5 m/s 15.5 m/s 17.5 m/s None of the above A 1500 kg automobile traveling east at 16 m/s collides, at an intersection, with a 2200 kg minivan traveling north at 15 m/s After collision the two vehicles get tangled and continue moving together. The total kinetic energy before and after collision is, respectively, KE_i and KE_f. The kinetic energy lost, KEi-KE_f is: 440 kJ 370 kJ 160 kJ 215 kJ None of the above

Answer 1

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