8/11/14 1 Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy Ben Travlun carries a 200 N suitcase up three flights of stairs (a height of 10.0 m) and then pushes it with a horizontal force of 50.0 N at a constant speed of 0.5 m/s for a horizontal distance of 35.0 meters. How much work does Ben do on his suitcase during this entire motion? W total = 3750 J Dr Emőke Bódis, Department of Biophysics, Medical School, UP Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy A force of 50 N acts on the block at the angle shown in the diagram. The block moves a horizontal distance of 3.0 m. How much work is done by the applied force? W = 129.9 J Dr Emőke Bódis, Department of Biophysics, Medical School, UP Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy A student with a mass of 80.0 kg runs up three flights of stairs in 12.0 sec. The student has gone a vertical distance of 8.0 m. Determine the amount of work done by the student to elevate his body to this height. Assume that her speed is constant. W = 6272 J Dr Emőke Bódis, Department of Biophysics, Medical School, UP Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy A tired squirrel (mass of 1 kg) does push-ups by applying a force to elevate its center-of-mass by 5 cm. Estimate the number of push-ups that a tired squirrel must do in order to do a approximately 5.0 Joules of work. 10 push-ups Dr Emőke Bódis, Department of Biophysics, Medical School, UP Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy Missy Diwater, the former platform diver for the Ringling Brother's Circus, had a kinetic energy of 12 000 J just prior to hitting the bucket of water. If Missy's mass is 40 kg, then what is her speed? v = 24.5 m/s Dr Emőke Bódis, Department of Biophysics, Medical School, UP Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy Consider a child on a sled sliding down a 100 m long hill on a 30° incline. The mass is 20 kg, and the person has a velocity of 2 m/s down the hill when they're at the top. How fast is the person traveling at the bottom of the hill? v = 31,3 m/s Dr Emőke Bódis, Department of Biophysics, Medical School, UP
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8/11/14
1
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
Ben Travlun carries a 200 N suitcase up three flights of stairs (a height of 10.0 m) and then pushes it with a horizontal force of 50.0 N at a constant speed of 0.5 m/s for a horizontal distance of 35.0 meters. How much work does Ben do on his suitcase during this entire motion? Wtotal = 3750 J
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
A force of 50 N acts on the block at the angle shown in the diagram. The block moves a horizontal distance of 3.0 m. How much work is done by the applied force? W = 129.9 J
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
A student with a mass of 80.0 kg runs up three flights of stairs in 12.0 sec. The student has gone a vertical distance of 8.0 m. Determine the amount of work done by the student to elevate his body to this height. Assume that her speed is constant. W = 6272 J
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
A tired squirrel (mass of 1 kg) does push-ups by applying a force to elevate its center-of-mass by 5 cm. Estimate the number of push-ups that a tired squirrel must do in order to do a approximately 5.0 Joules of work. 10 push-ups
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
Missy Diwater, the former platform diver for the Ringling Brother's Circus, had a kinetic energy of 12 000 J just prior to hitting the bucket of water. If Missy's mass is 40 kg, then what is her speed? v = 24.5 m/s
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
Consider a child on a sled sliding down a 100 m long hill on a 30° incline. The mass is 20 kg, and the person has a velocity of 2 m/s down the hill when they're at the top. How fast is the person traveling at the bottom of the hill? v = 31,3 m/s
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
8/11/14
2
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
A 2 kg ball is suspended from a 50 cm long rope as a pendulum. If it is released from point A and swings down to the point B (the bottom of its arc) and the angle changes by 30 degree: a) show that the velocity of the ball is independent of its mass, b) calculate the velocity of the ball at point B. v = 3.13 m/s
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
A roller coaster ride at an amusement park starts from rest at a height of 50 m above the ground and rapidly drops down along its track. At some point, the track does a full 360° loop which has a height of 20 m, before finishing off at ground level. The roller coaster train itself with a full load of people on it has a mass of 850 kg. vtop of the loop =24,45 m/s vat the bottom of the loop (i.e. ground level) =31,3 m/s
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
A mountain climber who is climbing a mountain in the Drakensberg during winter, by mistake drops her water bottle which then slides 100 m down the side of a steep icy slope to a point which is 10 m lower than the climber's position. The mass of the climber is 60 kg and her water bottle has a mass of 500 g . If the bottle starts from rest, how fast is it travelling by the time it reaches the bottom of the slope? (Neglect friction.) v=14 m/s What is the total change in the climber's potential energy as she climbs down the mountain to fetch her fallen water bottle? i.e. what is the difference between her potential energy at the top of the slope and the bottom of the slope? E=5880 J
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
What work does a baseball bat do on a baseball of mass 0.325 kg which has an initial speed forward of 36 m/s and a final speed of 27 m/s backwards. Assume motion is linear and horizontal. The work done by the bat is a non-conservative force. W = -92.1 J (Bad hit, the batter decreased the ebergy of the ball.)
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
How much work must be done to stop a 2000-kg car travelling at 60 km/h in 15.0 m? W = -2.78 105 J What was the average breaking force? F = 1,85 104 N
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
Premed Course, 14/07/08, Work, Energy, Conservation od Mechanical Energy
Two blocks are connected by a sting slung over a pulley as shown in the diagram below. The hanging block is allowed to drop. How fast will it be moving when it hits the ground? The block on the incline has mass MA = 2.50 kg. The hanging block has mass MB = 1.50 kg. The incline makes and angle θ = 30° with horizontal. Ignore friction.
Dr Emőke Bódis, Department of Biophysics, Medical School, UP
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