Question

1. A 30 N force is directed at an angle of 50° W of N x-component: A. -19 N B. -23 N C. -36 N D. 19N E. 23 N y-component: A. -19 N B. -23N C. -36 N D. 19 N E. 23 N west. What is the train's average acceleration? A. 10 kmh2,W B. 43 km/h2, w с. 10 kmh?. E D. 43km/h, E E. 53kmh?, E 2. The velocity of a train is 80 km/h west. One and a half hours later its velocity is 65 km/h 3. The "action and "reaction" forces of Newton's third law: A. are in the same direction B. have different magnitudes C. act on the same object D. act on different objects E. B&D 4. In the game of billiards, all balls have a mass of 0.17 kg. The cue ball, initially moving at 3 m/s E, collides with the 2 ball, initially at rest. After the collision, the 2 ball travels at 1.5 m/s in a direction of 60° S of E. What is the speed of the cue ball after the collision if it travels at an angle of 30o N of E? A. 1.5 m/s B. 1.8 m/s c. 2.6 m/s D. 4.3 m/s E. 5.2 m/s 5. A skier leaves the top of a slope with an initial speed of 5 m/s. Her speed at the bottom of the slope is 13 m/s. What is the height of the slope? B. 4.6 m C. 6.4 m D. 7.4 m E. 11m A. 1.1 m 6. The amount of energy needed to power a 0.1 KW light bulb for one minute would be just sufficient to lift a 1 kg object through a vertical distance of B. 75 m C. 100 m D. 120 m E. 610 m A. 12 m

Answer 1

Let v_x and v_y be the x-component & y-component respectively therefore v_x = 30N times cos 50 degree = 19.28N tildeequal 19N directed towards north (thatis j^cap) therefore correct option is: 19N v_y = 30N time sin 50 degree = 22.98N tildeequal 23N (directed towards west(thatis -i^cap)) therefore correct option: 23N(-i^cap) = -23N change in velocity (delta v) = 80km/hr -65km/hr = 15km/hr change in t6ime(delta t) = 1.5hr we know acceleration is given by delta v/delta t therefore a = 15km/hr/1.5hr a = 10km/hr^2 since the train is travelling towards west and the force is retarding in nature therefore the acceleration is directed towards east (thatis opposite to west) therefore required correct option: b10km/hr^2 newton's 3rd law states that every force has equal & opposite reaction which acts on the same body (thatis the body under the action of force) therefore by definition the correct option is: act on the same object from the diagram drawn aside: v_j & v_i are velocity of the