Slide 1 / 76 Slide 2 / 76 1 A driver in a 2000 kg Porsche wishes to pass a slow moving school bus on a 4 lane road. What is the average power in watts required to accelerate the sports car from 30 m/s to 60 m/s in 9 seconds? Work & Energy A 1,800 Multiple Choice Problems B 5,000 C 10,000 D 100,000 E 300,000 Slide 3 / 76 Slide 4 / 76 2 A force F is at an angle θ above the horizontal is 3 A force of 20 N compresses a spring with spring used to pull a heavy suitcase of weight mg a constant 50 N/m. How much energy is stored in distance d along a level floor at constant velocity. the spring? The coefficient of friction between the floor and the suitcase is μ. The work done by the force F is: A 2 J A Fdcos θ - μ mgd B 5 J B Fdcos θ C 4 J C -μ mgd D 6 J D 2Fdsin θ - μ mgd E 8 J E Fdcos θ - 1 Slide 5 / 76 Slide 6 / 76 4 A stone is dropped from the edge of a cliff. Which A 4 kg ball is attached to a 1.5 m long string and 5 of the following graphs best represents the stone's whirled in a horizontal circle at a constant speed of kinetic energy KE as a function of time t? 5 m/s. How much work is done on the ball during one period A 9 J C B 4.5 J A B C zero D 2 J E 8 J D E
Slide 7 / 76 Slide 8 / 76 6 A student pushes a box across a horizontal A force F is applied in horizontal to a 10 kg block. 7 surface at a constant speed of 0.6 m/s. The box The block moves at a constant speed 2 m/s across has a mass of 40 kg, and the coefficient of kinetic a horizontal surface. The coefficient of kinetic friction is 0.5. The power supplied to the box by friction between the block and the surface is 0.5. the person is The work done by the force F in 1.5 minutes is: A 9000 J A 40 W B 5000 J B 60 W C 3000 J C 150 W D 2000 J D 120 W E 1000 J E 200 W Slide 9 / 76 Slide 10 / 76 9 A ball swings from point 1 to point 3. Assuming 8 A ball swings from point 1 to point 3. Assuming the ball is in SHM and point 3 is 2 m above the the ball is in SHM and point 3 is 2 m above the lowest point 2. Answer the following questions. lowest point 2. Answer the following questions. What happens to the kinetic energy of the ball What is the velocity of the ball at the lowest point when it moves from point 1 to point 2? 2? A 2.2 m/s A increases B 3.5 m/s B decreases C 4.7 m/s C remains the same D 5.1 m/s D zero E 6.3 m/s E more information is required Slide 11 / 76 Slide 12 / 76 11 A 2 kg block released from rest from the top of an 10 A block with a mass of m slides at a constant incline plane. There is no friction between the velocity V 0 on a horizontal frictionless surface. The block and the surface. How much work is done by block collides with a spring and comes to rest the gravitational force on the block? when the spring is compressed to the maximum value. If the spring constant is K, what is the maximum compression in the spring? A 80 J V 0 (m/k) 1/2 A B 60 J B KmV 0 C 50 J C V 0 K/m D 40 J D m V 0 /K V 0 (K/m) 1/2 E 30 J E (V 0 m/K) 1/2 F
Slide 13 / 76 Slide 14 / 76 12 A 2 kg block released from rest from the top of an 13 A crane lifts a 300 kg load at a constant speed to incline plane. There is no friction between the the top of a building 60 m high in 15 s. The block and the surface. What is the speed of the average power expended by the crane to block when it reaches the horizontal surface? overcome gravity is: A 3.2 m/s A 10,000 W B 4.3 m/s B 12,000 W C 5.8 m/s C 15,000 W D 7.7 m/s D 30,000 W E 6.6 m/s E 60,000 W Slide 15 / 76 Slide 16 / 76 15 An apple of mass m is thrown in horizontal from 14 A satellite with a mass m revolves around Earth in the edge of a cliff with a height of H. What is the a circular orbit with a constant radius R. What is total mechanical energy of the apple with respect the kinetic energy of the satellite if Earth’s mass is to the ground when it is at the edge of the cliff? M? 2 A 1/2mv 0 A ½ mv B mgH B mgh 2 - mgH C ½ mv 0 ½GMm/R 2 C 2 D mgH - ½ mv 0 D ½ GMm/R 2 mgH + ½ mv 0 E E 2Mm/R Slide 17 / 76 Slide 18 / 76 17 A 500 kg roller coaster car starts from rest at point 16 An apple of mass m is thrown in horizontal from A and moves down the curved track. Ignore any the edge of a cliff with a height of H. What is the energy loss due to friction. Find the speed of the kinetic energy of the apple just before it hits the car at the lowest point B. ground? 2 + mgH A ½ mv 0 A 10 m/s 2 - mgH B ½ mv 0 B 20 m/s C mgH C 30 m/s 2 D ½ mv 0 D 40 m/s 2 E mgh - 1/2 mv 0 E 50 m/s
Slide 19 / 76 Slide 20 / 76 18 A 500 kg roller coaster car starts from rest at point A 19 Two projectiles A and B are launched from the and moves down the curved track. Ignore any ground with velocities of 50 m/s at 60 ̊ and 50 energy loss due to friction. Find the speed of the car m/s at 30 ̊ with respect to the horizontal. when it reaches point C. Assuming there is no air resistance involved, which projectile has greater kinetic energy when it reaches the highest point? A 10 m/s A projectile A B 20 m/s B projectile B C 30 m/s they both have the same none zero kinetic D 40 m/s C energy E 50 m/s they both have zero kinetic energy at the D highest point E more information is required Slide 21 / 76 Slide 22 / 76 20 An object with a mass of 2 kg is initially at rest 21 An object with a mass of 2 kg is initially at rest at at a position x = 0. A non-constant force F is a position x=0. A non-constant force F is applied applied to the object over 6 meters. What is to the object over 6 meters. What is the velocity the total work done on the object? of the object at 6 meters? A 200 J 150 m/s A B 150 J B 25 m/s C 170 J C 300 m/s D 190 J D 12.25 m/s E 180 J E not enough information Slide 23 / 76 Slide 24 / 76 22 A metal ball is held stationary at a height h 0 above 23 A toy car travels with speed v o at point x. Point Y the floor and then thrown upward. Assuming the is a height H below point x. Assuming there is no collision with the floor is elastic, which graph best frictional losses and no work is done by a motor, shows the relationship between the total energy E of what is the speed at point Y? the metal ball and its height h with respect to the floor? 2 ) 1/2 A (2gH+1/2v o B C A B v o -2gH 2 ) 1/2 C (2gH + v o 2 ) 1/2 D 2gH+(1/2v o D E E v o +2gH
Slide 25 / 76 Slide 26 / 76 24 A rocker is launched from the surface of a planet 25 A block of mass m is placed on a frictionless with mass M and radius R. What is the minimum inclined plane with an incline angle θ. The block is velocity the rocket must be given to completely just in contact with a free end of an unstretched escape from the planet's gravitational field? spring with a spring constant k. If the block is released from rest, what is the maximum compression in the spring? A (2GM/R) 1/2 A kmg sin θ B (2GM/R) 1/2 B kmg cos θ C (GM/R) 1/2 C 2mg sin θ /k D 2GM/R D mg/k E 2GM/16R 2 E kmg Slide 27 / 76 Slide 28 / 76 In a physics lab a student uses three light In a physics lab a student uses three light 27 26 frictionless PASCO lab carts. Each cart is loaded frictionless PASCO lab carts. Each cart is loaded with some blocks, each having the same mass. The with some blocks, each having the same mass. The same force F is applied to each cart and they move same force F is applied to each cart and they move equal distances d. Which cart will have more kinetic equal distances d. In which on of these three cases is more work done by force F? energy at the end of distance d? A cart I A cart I B cart II B cart II C cart III C cart III all three will have the the same work is done D D same kinetic energy on each E more information is required E more information is required Slide 29 / 76 Slide 30 / 76 In a physics lab a student uses three light 28 frictionless PASCO lab carts. Each cart is loaded with some blocks, each having the same mass. The same force F is applied to each cart and they move equal distances d. Which cart will move faster at the end of distance d? A cart I B cart II C cart III all three will move D with the same speed E more information is required
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