9 Q2 Seatwork #3: Law of Conservation of Mechanical Energy PDF

O.B. Montessori Center - Sta. Ana 2241 Pedro Gil Street,Sta. Ana, Manila 2425 G9 Q2 Seatwork #3: The Law of Conservation of Mechanical Energy Seatwork...

O.B. Montessori Center - Sta. Ana 2241 Pedro Gil Street,Sta. Ana, Manila 2425 G9 Q2 Seatwork #3: The Law of Conservation of Mechanical Energy Seatwork SCIENCE 9-Ruby AY 2425 (Student's Result) Name : John Tristan Aclaro Date : Dec 09, 2024 11:00 AM - 02:57 PM Remarks : Passed Activity Duration : 3 hour/s Score : 11.00 points/s Time Limit : 25.00 Items : 15 item/s Time Lapse : 10 mins 58 secs Passing Score : 8.00 point/s Teacher : DARREN LUCENA Objective: Direction: Read the questions/ statements and choose the BEST answer. Multiple Choice Review the result of your examination Wrong 1. When a roller coaster gains height, its potential energy decreases while its kinetic energy increases. (1 pt.) Correct answer: B False Your answer: A True Correct answer explanation: When a roller coaster gains height, its potential energy increases because potential energy is directly related to height. Simultaneously, its kinetic energy decreases because the roller coaster is moving more slowly as it climbs. Correct 2. As a skier descends a slope, the gravitational potential energy the skier had at the top is converted into kinetic energy. (1 pt.) Correct answer: A True Your answer: A True Correct answer explanation: The increase in kinetic energy is exactly equal to the decrease in gravitational potential energy, following the principle of conservation of mechanical energy. Wrong 3. When a diver leaps off a platform, the total mechanical energy of the diver remains constant throughout the dive if there is no air resistance. (1 pt.) Correct answer: A True Your answer: B False Correct answer explanation: The conservation of mechanical energy principle states that the total mechanical energy in a closed system without non-conservative forces (like friction) is constant. Correct 4. A pendulum reaches its maximum velocity when it is at its lowest point. This means that its potential energy is greatest at this point. (1 pt.) Correct answer: B False Your answer: B False Correct answer explanation: At the lowest point of its swing, a pendulum reaches its maximum velocity because it has converted most of its potential energy into kinetic energy. Consequently, its potential energy is at its minimum at this point. Correct 5. A diver who jumps off a diving board 10 feet above the ground has the lowest gravitational potential energy just before the jump. (1 pt.) Correct answer: B False Your answer: B False Correct answer explanation: Just before the jump, the diver is at the highest point of the diving board, so the height is at its maximum. Consequently, the gravitational potential energy (GPE) is at its highest just before the jump. Wrong 6. Which of the following is NOT TRUE about the law of conservation of mechanical energy? (1 pt.) Correct answer: B Energy is created when an object is increasing in speed and an energy is lost when an object begins to slow down. Your answer: A The total mechanical energy of an object is constant all throughout its motion. Correct answer explanation: Energy is not created or lost; it is transformed from one form to another. When an object increases in speed, its kinetic energy increases, but this increase comes at the expense of a decrease in potential energy if the object is falling. No energy is cre Correct 7. Maria throws a 250-g rock vertically upwards from ground level with an initial speed of 15 m/s. The rock's total mechanical energy at the start is 28.13 J. What is the rock’s total mechanical energy after 3 seconds? (1 pt.) Correct answer: B 28.13 J Your answer: B 28.13 J Correct answer explanation: According to the law of conservation of energy the total mechanical energy (TME) of an object remains constant throughout its motion. Hence, at any point during the rock’s motion, the total mechanical energy of the object is still 28.13 J. Correct 8. Maria throws a 250-g rock vertically upwards from ground level with an initial speed of 15 m/s. The rock's total mechanical energy at the start is 28.13 J. What is the rock’s total mechanical energy at the peak? (1 pt.) Correct answer: B 28.13 J Your answer: B 28.13 J Correct answer explanation: According to the law of conservation of energy the total mechanical energy (TME) of an object remains constant throughout its motion. Hence, at any point during the rock’s motion, the total mechanical energy of the object is still 28.13 J. Correct 9. A 20-kg object is dropped from the edge of a cliff. It falls freely and reaches the ground 80 meters below. The object's total mechanical energy at the edge of the cliff is 15680 J. At which of the following heights does the object have the highest potential energy? (1 pt.) Correct answer: A 80 m above the ground Your answer: A 80 m above the ground Correct answer explanation: The object has the highest potential energy when it is at the highest point, which is at the edge of the cliff (80 meters). Correct 10. A 20-kg object is dropped from rest from the edge of a cliff. It falls freely and reaches the ground 80 meters below. The object's total mechanical energy at the edge of the cliff is 15680 J. What is the object's kinetic energy at the moment it is launched? (1 pt.) Correct answer: A 0 J Your answer: A 0 J Correct answer explanation: Since the object is dropped from the edge of the cliff, it starts with no initial velocity, meaning it has no initial kinetic energy at the moment it is dropped. Correct 11. A bungee jumper is preparing to jump from a bridge that is 60 meters above a river. Including the jumper and the bungee cord, the total mass is 80 kg. The total mechanical energy of the jumper and the bungee cord system is 47040 J. What is the bungee jumper’s gravitational potential energy before the jump? (1 pt.) Correct answer: C 47040 J Your answer: C 47040 J Correct answer explanation: At the starting point (before the jump), all the total mechanical energy is in the form of gravitational potential energy. Correct 12. A bungee jumper is preparing to jump from a bridge that is 60 meters above a river. Including the jumper and the bungee cord, the total mass is 80 kg. The total mechanical energy of the jumper and the bungee cord system is 47040 J. What is the object’s kinetic energy at its starting point? (1 pt.) Correct answer: A 0 J Your answer: A 0 J  Correct answer explanation: At the starting point, the bungee jumper is at rest, so the velocity is zero. Since kinetic energy depends on velocity the kinetic energy at the starting point is 0 J. Wrong 13. A bungee jumper is preparing to jump from a bridge that is 60 meters above a river. Including the jumper and the bungee cord, the total mass is 80 kg. The total mechanical energy of the jumper and the bungee cord system is 47040 J. What is the bungee jumper’s total mechanical energy at a height of 25 meters above the river? (1 pt.) Correct answer: C 47040 J Your answer: D 78400 J Correct answer explanation: The total mechanical energy is conserved throughout the motion of the jumper. So, no matter the height, the total mechanical energy remains constant at 47040 J. Correct 14. A bungee jumper is preparing to jump from a bridge that is 60 meters above a river. Including the jumper and the bungee cord, the total mass is 80 kg. The total mechanical energy of the jumper and the bungee cord system is 47040 J. What is the total mechanical energy of the jumper once the bungee cord has stretched to its maximum length? (1 pt.) Correct answer: C 47040 J Your answer: C 47040 J Correct answer explanation: The total mechanical energy remains constant throughout the jumper's fall and stretch of the bungee cord. At maximum stretch, the mechanical energy is still 47040 J. Correct 15. A bungee jumper is preparing to jump from a bridge that is 60 meters above a river. Including the jumper and the bungee cord, the total mass is 80 kg. The total mechanical energy of the jumper and the bungee cord system is 47040 J. What is the bungee jumper’s gravitational potential energy when it reaches the surface of the river? (1 pt.) Correct answer: A 0 J Your answer: A 0 J Correct answer explanation: At the surface of the river, the jumper has no height above the river, and since gravitational potential energy depends on height, the potential energy is zero. Powered by TCPDF (www.tcpdf.org)