Slide 1 / 41 Slide 2 / 41 1 After firing a cannon ball, the cannon moves in the opposite direction from the ball. This an example of: A Newton’s First Law B Newton’s Second Law AP Physics C C Newton’s Third Law Dynamics D Newton’s Law of Gravitation Multiple Choice E None of the above www.njctl.org Slide 3 / 41 Slide 4 / 41 2 In the absence of an external force a moving object will 3 A loaded truck collides with a car causing a large amount of damage to the car. Which of the following is true about the collision? A slow down and come to a stop A The force on the truck is greater than the force on the car. B speed up B The force on the car is greater than the force on the truck C move with a constant speed in a straight line C The force on the truck is the same in magnitude as the force on the car D turn to the right D During the collision, the truck has a greater displacement E turn to the left than the car E During the collision, the truck has a greater acceleration than the car Slide 5 / 41 Slide 6 / 41 4 An object is thrown straight up. How do we compare the net force 5 An elevator car weighs 5500 N. If the car accelerates upwards at a on the object to its weight when it is at the highest point in the rate of 4.0 m/s 2 , what is the tension in the support cable lifting the path? car? Use g = 10 m/s 2 . A It is greater than the weight A 1600 N B is slightly less than the weight B 3300 N C is zero C 4400 N D It is equal to the weight D 7700 N E It can’t be determined E 8700 N
Slide 7 / 41 Slide 8 / 41 6 Which of the following diagrams best 7 A block with a mass m = 5 kg slides down an inclined plane with an represents the gravitational force W, the angle θ = 37°. The block maintains a constant acceleration a = 5.6 frictional force f, and the normal force N that m/s2. (sin37° = 0.6, cos37° = 0.8). The coefficient of kinetic friction act on the block sliding down the inclined between the block and the inclined surface is 0.05. What is the plane as shown above? normal force on the block? B C A A 50 N B 40 N E D C 30 N D 20 N E 10 N Slide 9 / 41 Slide 10 / 41 8 A block with a mass m = 5 kg slides down an inclined plane with an 9 The coefficient of static friction between the block and the inclined angle θ = 37°. The block maintains a constant acceleration a = 5.6 plane is 0.4 and θ=25 0 . The block is placed on the inclined plane. m/s 2 . (sin37° = 0.6, cos37° = 0.8). The coefficient of kinetic friction The block will: between the block and the inclined surface is 0.05. What is the friction force between the block and inclined plane? A not move A 2 N B start moving down the incline and then stop before it B 5 N reaches the bottom of the incline C 6 N C start moving down the incline and continue to increase its velocity D 30 N D start moving and increase its acceleration until it reaches the E 40 N bottom of the incline E start moving and then its acceleration will decrease Slide 11 / 41 Slide 12 / 41 10 A system of two blocks is accelerated by an applied force of 11 A student pulls a wooden box along a rough horizontal floor at magnitude F on the frictionless horizontal surface. The tension in constant speed by means of a force P as shown to the right. Which the string between the blocks is: of the following must be true? A 3 F A P > f and N < W B 5 F B P > f and N = W C 3/8 F C P = f and N > W D 1/3 F D P = f and N = W E 1/5 F E P < f and N = W
Slide 13 / 41 Slide 14 / 41 12 As shown below, a boy pushes a sled of mass m across a rough 13 A block of mass m is pulled along a horizontal surface at constant horizontal surface by applying a force of magnitude F directed at speed v by a force Fapp , which acts at an angle of θ with the an angle θ. The normal force on the sled is: horizontal. The normal force exerted on the block by the surface is: A mg A mg - Fapp cosθ B mg sinθ B mg - Fapp sinθ C mg cosθ C mg D mg + F sinθ D mg + Fapp sinθ E mg – F sinθ E mg + Fapp cosθ Slide 15 / 41 Slide 16 / 41 14 An ideal spring obeys Hooke's law, F = -kx. A mass of 0.30 kg 15 A block with a mass m is placed on the top of an identical block m hung vertically from this spring stretches the spring 0.015 meter. and the system of two blocks is at rest on a rough horizontal The value of the spring constant is nearly surface as shown below. The top block is tied to the wall. The coefficient of static friction between all surfaces is µ s . What maximum value does force F reach before the lower block starts A 150 N/m sliding to the left? B 200 N/m A 3 µ s mg C 300 N/m B 2 µ s mg D 250 N/m C 4 µ s mg E 350 N/m D ½ µ s mg E ¼ µ s mg Slide 17 / 41 Slide 18 / 41 16 Three blocks connected with each other by two light strings. The 17 A lamp of mass m is suspended from two cables of unequal length blocks have different masses m 2 > m 3 >m 1 . The heaviest of three as shown to the right. Which of the following is true about the blocks is placed on a frictionless table. The system of three blocks tensions T 1 and T 2 in the cables? is released from rest. What is the acceleration of block m 2 ? A (m 2 - m 3 - m 1 )g/(m 1 + m 2 + m 3 ) A T 1 > T 2 B (m 1 - m 3 - m 2 )g/(m 1 + m 2 + m 3 ) B T 1 = T 2 C (m 3 - m 1 )g/(m 1 + m 2 + m 3 ) C T 2 > T 1 D (m 3 - m 2 - m 1 )g/(m 1 + m 2 + m 3 ) D T 1 - T 2 = mg E (m 1 - m 3 )g/(m 1 + m 2 + m 3 ) E T 1 + T 2 = mg
Slide 19 / 41 Slide 20 / 41 18 A ball of mass m is suspended from two massless strings of an 19 A ball moves horizontally with an initial velocity vo, as shown equal length as shown below. The tension force in each string is: above. It is then struck by a tennis racket. After leaving the racket, the ball moves with a velocity v. Which of the following vectors best represents the direction of the average force that the racket exerts A ½ mgcosθ on the ball? B 2mgcosθ A C mgcosθ B D mg/(cosθ ) E mg/(2cosθ ) C D E Slide 21 / 41 Slide 22 / 41 20 A marble of mass m moves along a path with a speed defined by 21 The position as a function of time of a moving object is given by the the function v = bt 2 + c, where t is time and b and c are constants. formula x = 2t 3 - 3t 2 + 4t. At what time the net force on the object is What is the magnitude F of the net force on the particle at time t = zero? t 1 ? A 0.5 s bt 1 2 + c A B 1.0 s 3mbt 1 + 2c B C 1.5 s mbt 1 C D 1.8 s mbt 1 + c D E 2.2 s 2mbt 1 E Slide 23 / 41 Slide 24 / 41 22 The velocity as a function of time of a moving 23 A box of 50 kg is pulled up from rest by a cable. The tension force object is shown by the graph. Which of the in the cable is 600 N. What is the box’s velocity after it covers following graphs best represents the vertical distance of 16 m? magnitude of the net force exerted on the object as a function of time? B A 4 m/s A B 8 m/s C 12 m/s D 16 m/s E D C E 20 m/s
Slide 25 / 41 Slide 26 / 41 24 An Atwood machine is presented by the diagram. What is the 25 A 12 kg sphere is supported by two ropes AB and BC. What is the magnitude of the acceleration of 0.5 kg block? tension force in rope BC? A 6 m/s 2 A 120 N B 4 m/s 2 B 160 N C 2 m/s 2 C 180 N D 1 m/s 2 D 200 N E 0.5 m/s 2 E 240 N Slide 27 / 41 Slide 28 / 41 26 A 12 kg sphere is supported by two ropes AB and BC. What is the 27 A small sphere is attached to a light string that can move in a tension force in rope AB? vertical circle. The sphere is released from point 1 and describes a semicircle when it reaches point 2. What are the directions of the acceleration vector at point 1 and point 2? Point 1 Point 2 A 120 N A Downward Upward B 160 N B Downward To the right C 180 N C Upward Upward D 200 N D To the right Upward E 240 N E To the right Downward Slide 29 / 41 Slide 30 / 41 28 A particle moves along a curved path from point 1 to point 2. Which 29 A 12 kg block is suspended from two light, identical springs. When of the following diagrams indicates a possible combination of the the block is in equilibrium the springs stretch by 30 cm. What is the net force, acceleration and velocity of the particle? spring constant of each spring? B C A A 50 N/m B 100 N/m C 120 N/m E D D 160 N/m E 200 N/m
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