Name: Answer Key Date: Regents Physics. Projectiles

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1 Nae: Anwer Key Date: Regent Phyic Tet # 5 Review 1. Equation to know: Projectile (1) A y = Ainθ () A = Acoθ Δv vf vi vf + vi (3) a= = (4) vavg = (5) d=vit+½at Δ t tf ti (6) v f =vi+at (7) vf =vi +ad. Ter to know: vector, agnitude, direction, reultant, coponent, trajectory, projectile 3. Read Chapter A ball i launched horizontally off a building. At the ae tie, a ball i dropped off the building. For the two ball, copare: o the tie taken to reach the ground Both hit at the ae tie o initial velocitie in the and y direction V i in y direction = 0 for both, in = 0 for dropped ball. Launched ball V i = oe value. o the acceleration a = / for both ball o the diplaceent in the and y direction. d y i ae for both, d = 0 for dropped, d = oe value for launched. 5. A occer ball i kicked with an initial velocity of 15 / at an angle of 30 0 above the horizontal. Decribe what happen to the vertical and horizontal coponent of it velocity a the football flie through the air and land. Vertical velocity decreae until it hit top of path and then increae a head back down. Horizontal velocity reain the ae (no horizontal acceleration) Direction: Read each quetion carefully and record your anwer in the pace provided. Be ure to how all work! Anwer hould be in ignificant figure. You will be graded on proper ue of the GUESS ethod. Thee will be the ae direction on the tet. Practice the GUESS ethod now. 6. A tone i thrown horizontally at a peed of 5.0 / fro the top of a cliff 78.4 high. a) How long doe it take the tone to reach the botto of the cliff? d (78.4 ) t = = = 4.00 a 9.81 b) How far fro the bae of the cliff doe the tone trike the ground? d = v t = 5.0 (4.00 ) = 0. c) What are the horizontal and vertical coponent of the velocity of the tone jut before it trike the ground? vfy = viy + at = ( 9.81 )(4.00 ) = 39. / down v = 5.0 / forward f 7

2 7. A player kick a football fro ground level at 7 / at an angle of 35 0 above the horizontal. Calculate the following. a) the and y coponent of the initial velocity. v = v inθ = 7 (in35 ) = 15 / up iy i v = v coθ = 7 (co35 ) = / forward b) the total tie the ball i in the air. i i t top vf vi 15 / = = = 1.5 a 9.81 t = ( t ) = (1.5 ) = 3.0 total top c) the ditance the ball travel (horizontally) before it hit the ground. d) it aiu height. d = v t = (3.0 ) = 66 total d = v t + at = (15 )(1.5 ) + ( 9.81 )(1.5 ) = y iy top top 8. A ball i rolled down a rap and projected horizontally fro a height of 1.7 eter. It land.6 eter away. Calculate it initial peed. [Note: Thi i iilar to the Shoot for Your Grade Lab] Step 1 Solve for tie uing the height dy (1.7 ) t = = = g 9.81 d.6 Step Ue the tie and ditance to olve for v vi = = = 4.4 / t The ball fro quetion 8 i now raied to a height of.4 eter. Where i it going to land? [Hint: The initial velocity doe not change with a height change.] Step 1 Solve for new tie uing the new height dy (.4 ) t = = = g 9.81 Step Ue the new tie and v fro #8 to olve for d d = v t = 4.4 (0.699 ) = 3.1 8

3 Bae your anwer to quetion on the following inforation. A rock i launched at a peed of 10. / at an angle of with the horizontal. It return to the earth at the ae level at which it wa launched. 10. The hape of the path that the rock took wa: (A) traight line (B) circular (C) parabolic (D) hyperbolic 11. The initial vertical velocity of the rock i: (A) 5.0 / (B) 8.7 / (C) 10. / (D) 0. / 1. The initial horizontal velocity of the rock i: (A) 5.0 / (B) 8.7 / (C) 10. / (D) 0. / 13. Which tateent i true about the trajectory of the rock? (A) It accelerate in both the vertical and horizontal direction (B) It accelerate in the vertical direction and travel at a contant velocity in the horizontal direction. (C) It accelerate in the horizontal direction and travel at a contant velocity in the vertical direction (D) It travel at a contant velocity in both the horizontal and vertical direction Quetion 14 and 15 refer to the following: Projectile A i launched horizontally at a peed of 0. eter per econd fro the top of a cliff and trike a level urface below, 3.0 econd later. Projectile B i launched horizontally fro the ae location at a peed of 30. eter per econd. 14. How uch tie doe it take projectile B to reach the level urface? (A) 10. (B) 4.5 (C) 3.0 (D) Approiately how high i the cliff? (A) 9 (B) 44 (C) 60. (D) A ball i thrown at an angle of 38 0 to the horizontal. What happen to the agnitude of the ball vertical acceleration during the total tie interval that the ball i in the air? (A) It increae, then decreae. (B) It decreae, then increae. (C) It decreae, then reain the ae (D) It reain the ae 17. A football player kick a ball with an initial velocity of 5 eter per econd at an angle of 53 0 above the horizontal. What i the vertical coponent of the initial of the initial velocity of the ball? (A) 0. / (B) 5 / (C) 15 / (D) 10. / 9

4 Quetion 18 through 0 refer to the following: A ball i thrown horizontally with an initial velocity of 0.0 eter per econd fro the top of a tower 60.0 eter high, a hown in the diagra below. 18. What i the horizontal velocity of the ball jut before it reache the ground? (A) 0. / (B) 9.81 / (C) 34.3 / (D) 68.6 / 19. What i the approiate total tie required for the ball to reach the ground? (A).04 (B) 3.00 (C) 3.50 (D) What i the initial vertical velocity of the ball? (A) 60.0 / (B) 0.0 / (C) 9.81 / (D) 0 / 1. The diagra below how a tudent throwing a baeball horizontally at 5 eter per econd fro a cliff 45 eter above level ground. Approiately how far fro the bae of the cliff doe the ball hit the ground? [Neglect air reitance] (A) 45 (B) 75 (C) 140 (D) 30. A book i puhed with an initial horizontal velocity of 5.0 eter per econd off the top of a dek. What i the initial vertical velocity of the book? (A) 5.0 / (B) 10 / (C).5 / (D) 0 / 0

5 3. Which graph bet repreent the otion of an object whoe peed i increaing? 4. A projectile i launched with an initial velocity of 00 eter per econd at an angle of 30 0 above the horizontal. What i the agnitude of the vertical coponent of the projectile initial velocity? (A) 00 in30 (C) 00 co 30 (B) 00 / (D) 00 / in30 co 30 Quetion 5 and 6 refer to the following: A golf ball leave a golf club with an initial velocity of 40.0 eter per econd at an angle of with the horizontal. 5. What i the vertical coponent of the golf ball initial velocity? (A) 5.7 / (B) 40.0 / (C) 30.6 / (D) 61.3 / 6. What i the total horizontal ditance traveled by the golf ball during the firt.50 econd of flight? (A) 40.0 (B) 64.3 (C) 76.6 (D) 100. Anwer: 6. a b. 0. c. v = 5.0 / vy = / 7. a. v = / Vy = 15 / b. 3.0 c. 66 d / C 11. B 1. A 13. B 14. C 15. B 16. D 17. A 18. A 19. C 0. D 1. B. D 3. A 4. A 5. A 6. C 1

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