Скачать презентацию Springs Power and Friction Power Friction Springs Скачать презентацию Springs Power and Friction Power Friction Springs

7e5cbd73d794710e71019f57a9159381.ppt

  • Количество слайдов: 17

Springs, Power and Friction Springs, Power and Friction

Power Friction Springs 10 10 10 20 20 20 30 30 30 40 40 Power Friction Springs 10 10 10 20 20 20 30 30 30 40 40 40 50 50 50

Power – 10 Points QUESTION: • Your toaster uses 7200 Joules every hour and Power – 10 Points QUESTION: • Your toaster uses 7200 Joules every hour and therefore has this power in Watts. ANSWER: • What is 2 W?

Power – 20 Points QUESTION: • You have four 50 W lightbulbs in your Power – 20 Points QUESTION: • You have four 50 W lightbulbs in your room. You study with them on for 2 hours a day for one week and use this much energy in k. Wh. ANSWER: • What is 2. 8 k. Wh?

Power – 30 Points QUESTION: • You want to lift a 900 kg elevator Power – 30 Points QUESTION: • You want to lift a 900 kg elevator up 30 stories (120 m). The elevator needs to ascend at a rate of 5 seconds per story. You buy a motor with this many Watts of power. ANSWER: • What is 7056 W?

Power – 40 Points QUESTION: • Your 1200 kg car is travelling 10 m/s Power – 40 Points QUESTION: • Your 1200 kg car is travelling 10 m/s and uses friction to stop over 5 s. Thermal energy is generated in this process with this power. ANSWER: • What is 12000 W?

Power – 50 Points QUESTION: • You find a 10 m high waterfall where Power – 50 Points QUESTION: • You find a 10 m high waterfall where 1000 kg of water flow over it every second. If you set up a turbine to convert the water’s KE at the bottom of the waterfall into electricity, your turbine produces enough power to light this many 100 -W lightbulbs. ANSWER: • What is 980 lightbulbs?

Friction – 10 Points QUESTION: • Your 1000 kg car is travelling 5 m/s Friction – 10 Points QUESTION: • Your 1000 kg car is travelling 5 m/s and then uses friction to stop. Friction did this much work in J. ANSWER: • What is - 12500 J?

Friction – 20 Points QUESTION: • A 500 kg rollercoaster starts off on an Friction – 20 Points QUESTION: • A 500 kg rollercoaster starts off on an 80 m high hill. If friction does -100, 000 J of work between the first hill and the second, the second hill must be this high. ANSWER: • What is 60 m?

Friction – 30 Points QUESTION: • A cross-country skier crosses a patch of snow Friction – 30 Points QUESTION: • A cross-country skier crosses a patch of snow with coefficient of friction = 0. 1. If she starts off going 10 m/s, she travels this far along the snow before friction stops her. ANSWER: • What is 51 m?

Friction – 40 Points QUESTION: • A 10 -m tall grassy hill has a Friction – 40 Points QUESTION: • A 10 -m tall grassy hill has a coefficient of friction of 0. 15 and a slope of 30 degrees. A box moves this fast at the bottom of this hill. ANSWER: • What is 12. 0 m/s?

Friction – 50 Points QUESTION: • A 10 m tall grassy hill has a Friction – 50 Points QUESTION: • A 10 m tall grassy hill has a coefficient of friction of 0. 12. If a box is moving 10 m/s at the bottom of the hill, the hill has this slope. ANSWER: • What is 13. 8 degrees?

Springs – 10 Points QUESTION: • A spring of spring constant k = 100 Springs – 10 Points QUESTION: • A spring of spring constant k = 100 N/m is stretched 0. 1 m. The spring stores this much spring potential energy. ANSWER: • What is 0. 5 J?

Springs – 20 Points QUESTION: • To store 50 J of PEs, a spring Springs – 20 Points QUESTION: • To store 50 J of PEs, a spring with spring constant k = 150 N/m is stretched this far. ANSWER: • What is 0. 82 m?

Springs – 30 Points QUESTION: • A spring with spring constant k = 40 Springs – 30 Points QUESTION: • A spring with spring constant k = 40 N/m stores 100 J of energy. At that point, the spring pulls back with this much force in N. ANSWER: • What is 89. 4 N? (or -89. 4 N if pulling down or left)

Springs – 40 Points QUESTION: • A bungee jumper of mass m = 50 Springs – 40 Points QUESTION: • A bungee jumper of mass m = 50 kg falls 20 meters before the bungee stretches and 20 meters while it stretches. This is the bungee’s spring constant in N/m. ANSWER: • What is 98 N/m?

Springs – 50 Points QUESTION: • A bungee jumper of mass m = 75 Springs – 50 Points QUESTION: • A bungee jumper of mass m = 75 kg falls 20 meters before her bungee (of k = 56 N/m) stretches. She stretches the bungee this far. ANSWER: • What is 24. 3 m?