Practice First Exam Spring 2000 PHY 2053 Bernard F. Whiting1 A ball is thrown vertically down with a velocity of 2.5 m/s from the top of a building ofheight 210 m. Simultaneously, a second ball is launched upward from the ground at avelocity of 39.5 m/s. At what height above the ground will the two balls meet?1) 125 m 2) 25 m 3) 75 m 4) 175 m 5) none of these2 Hansel and Gretel leave home and go into the woods, travelling 1000 m at 37° N of W.They then run out of bread crumbs, and promptly get lost. After wandering for sometime, it dawns on them to use the compass they have brought with them. They thentravel 200 m due W and find themselves at the witch’s hut, which is 2 km N of the homefrom which they had started. How far, and in what direction, did they travel while lost?1) 1.51 km, 35° E of N 2) 1720 m, 55° N of E 3) 1240 m, 53° W of N 4) 2000 m, S 5) 0.5 km, 37° S of W3 Megan drives from Gainesville to Orlando at a speed of 120 km/hr, promptly turnsround, and drives leisurely back to Gainesville at a speed of 80 km/hr. Find her averagespeed for the trip.1) 106 km/hr 2) 100 km/hr 3) 112 km/hr 4) 91 km/hr 5) 96 km/hr4 A plane starts from rest, and accelerates along the ground before take-off. It moves 600m in 12 s. Assuming constant acceleration, find the speed of the plane at the end of 12 s.1) 70 m/s 2) 100 m/s 3) 60 m/s 4) 80 m/s 5) 90 m/s5 A speeding motorist travelling at 120 km/hr passes a stationary police officer. Theofficer immediately begins pursuit at a constant acceleration of 2.8 m/s2. How fast willthe police officer be travelling when he catches the speeder, assuming the speedermaintains a constant speed? Hint: hold off using numbers until the end.1) 120 km/hr 2) 150 km/hr 3) 210 km/hr 4) 240 km/hr 5) 185 km/hr6 An airplane is flying at a constant altitude of 100 m over the ocean at a speed of 100m/s. The pilot is on a rescue mission and plans to drop a care package so that it landson a ship’s deck. The ship is stationary in the water and directly in front of the plane. Atwhat horizontal distance from the ship should the pilot release the package?1) 452 m 2) 301 m 3) 402 m 4) 251 m 5) 352 m7 A rock is launched at an angle θ with respect to the level ground at a speed of v. Therock lands a distance R from the launch point. Which one of the following is a correctformula for the total time of flight of the rock, where g is the magnitude of theacceleration due to gravity?1) 2 v sin θ / g 2) R / v sin θ 3) v / g 4) v cos θ / g 5) R cos θ / v8 A rock is shot at a speed of 50 m/s at an angle of 60° from the horizontal towards a highcliff 100 m away. Assume the base of the cliff is at the same altitude as the launch site.At what height does the rock strike the cliff?1) 126 m 2) 187 m 3) 173 m 4) 95 m 5) 154 m9 A ball is thrown directly downward with an initial speed of 10 m/s from the top of a towerof unknown height. The speed of the ball just before impact with the ground is 25 m/s.What is the height of the tower in meters?1) 33 2) 53 3) 47 4) 27 5) 1610 An ultralight airplane has a true airspeed of 30 km/hr due East. The airplane’sgroundspeed, however, is observed to be just 20 km/hr due North. What is the speedand direction of the wind?1) 50 km/hr, 34° North of West 2) 36 km/hr, 34° North of West 3) 36 km/hr, 56°North of East 4) 10 km/hr, due North 5) 36 km/hr, 34° North of East11 A projectile is to be launched at an angle such that it impacts at a distance 100 mdownrange 5.0 seconds after launch. What must be the launch angle?1) 39° 2) 17° 3) 57° 4) 45° 5) 51° 12 A ball rolls off the edge of a table 0.90 m high, and strikes the floor a distance 3.4 mfrom the base of the table. What is the balls speed as it leaves the edge of the table?1) 6.7 m/s 2) 7.1 m/s 3) 7.9 m/s 4) 5.0 m/s 5) 5.6 m/s 13 The water in a 300 m wide river flows at 1.0 m/s. A canoeist, whose speed relative tothe water is 2.5 m/s, orients his boat so as to cross the river to a point on the far bankdirectly opposite his starting point. How long will the crossing take?1) 120 sec. 2) 131 sec. 3) 86 sec 4) 300 sec. 5) 200 sec14 A car’s speed as a function of time is given by v(t) = (3.0 m/s) + (0.20 m/s3) t 2. What isits average acceleration for the time interval from t = 0.0 to t = 5.0 seconds?1) 1.6 m/s22) 0.6 m/s23) 1.0 m/s24) 2.0 m/s25) 2.2 m/s215 A rock is shot from the back of a truck moving at 100 m/s along a straight horizontalroad. The launch device is aimed vertically upward, perpendicular to the ground. If airresistance can be neglected, where will the rock fall?1) on the truck 2) in front of the truck 3) behind the truck4) it depends on the launch speed 5) it depends on the value of g 16 One can reach Palonka by riding a bicycle 15 km due West, then 5 km due South, andfinally 10 km 30° South of East. The magnitude of the resulting total displacement is:1) 17.4 km 2) 8.7 km 3) 6.4 km 4) 30 km 5) 11.8 km 17 You drive the 45 km from Gainesville to Ocala at a speed of 90 km/hr. After taking a 30min. rest in Ocala, you drive back to Gainesville at 60 km/hr. What is your averagespeed for the whole trip?1) 36 km/hr 2) 63 km/hr 3) 44 km/hr 4) 51 km/hr 5) 72 km/hr 18 A particle going due North at 5 m/s is deflected so that it moves due East at 5 m/s. Thechange in velocity is a vector pointing:1) S of E 2) N of E 3) E 4) S 5) N of W 19 A body moves with a constant speed in a straight line. Which statement MUST be true?1) No force acts on the body2) A net force of zero acts on the body3) A constant force acts on the body, in the direction opposite the motion4) A constant net force acts on the body in the direction of the motion5) A single constant force acts on the body in the direction of the motion20 A car travelling at 60 km/hr strikes a tree. The front of the car collapses and the drivercomes to rest in 0.70 m. If, during the collision, the acceleration of the driver is constant,find the magnitude of this acceleration. Give …