Energy is conventionally measured in Calories as well as in joules. One Calorie in nutrition is one kilocalorie, defined as 1 kcal = 4 186 J.
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Chapter 8 Solutions
Physics for Scientists and Engineers
- Under normal conditions the human heart converts about 13.2 J of chemical energy per second into 1.32 W of mechanical power as it pumps blood throughout the body. HINT (a) Determine the number of Calories required to power the heart for one day, given that 1 Calorie equals 4186 J. Cal (b) Metabolizing 1 kg of fat can release about 9000 Calories of energy. What mass of metabolized fat (in kg) would power the heart for one day? kgarrow_forwardat an amusement park, a swimmer uses a water slide to enter the main pool.the swimmer slides without friction, and descends through a vertical height of 2.49m. find the swimmers speed at the bottom of the slide if she starts with an initial speed of 0.850m/sarrow_forwardEmma rides a barrel over Niagara Falls. The barrel is moving at 7.50m/s as it goes over the top of the falls, which are 99.0m high. Assuming there is no friction, how fast is it moving when it hits the bottom?arrow_forward
- An athlete jumps over a barrier with an initial speed of 2.2 m/s. How much will the athlete be raised during the jump?arrow_forwardYou are driving to work at 60 mph and need to accelerate to 75 mph. How long will it take to reach this speed? Express this quantity in units of seconds. Assume the engine is rated at 140 hp and is 25% efficient. The combined vehicle and driver mass is 2970 lbm.arrow_forwardThe fastest that a human has run is about 12 m/s. (a) If a pole vaulter could run this fast and convert all of her kinetic energy into gravitational potential energy, how high would she go (in m)? m (b) Compare this height with the world record in the pole vault. (The world record in the pole vault for women is 5.06 m.) h12 m/s hWR =arrow_forward
- A race car with a mass of 1850 kg accelerates from rest down a race track at a rate of 21.0 m/s2. If the track is 400m long, what is the gain in kinetic energy of the car when it reaches the end of the track?arrow_forwardA 50.0 kg cheetah accelerates from rest to its top speed of 30.3 m/s. (a) How much net work (in J) is required for the cheetah to reach its top speed? (b) One food Calorie equals 4186 J. How many Calories of net work are required for the cheetah to reach its top speed? Note: Due to inefficiencies in converting chemical energy to mechanical energy, the amount calculated here is only a fraction of the energy that must be produced by the cheetah's body.arrow_forwardUnder normal conditions the human heart converts about 13.5 J of chemical energy per second into 1.35 W of mechanical power as it pumps blood throughout the body. (a) Determine the number of Calories required to power the heart for one day, given that 1 Calorie equals 4186 J. ______________ Cal (b) Metabolizing 1 kg of fat can release about 9000 Calories of energy. What mass of metabolized fat (in kg) would power the heart for one day? ________________kgarrow_forward
- What is the kinetic energy of 1 kg of air (about 1 m3) moving at 15 m/s (about 32 mph)? If it takes 2 seconds to raise an 8 kg block a vertical height of 1 m, what is the power expended?arrow_forwardA typical human brain has a mass of 1.4 kg, which makes up about 2% of a person's mass. However, the brain requires 20% of the body's power consumption. In essence, the brain requires 10 times as much power as any other organ in the body. The average power output of the human brain is about 2.0*10^1 W. Assume that the brain's power output could be converted into mechanical work and calculate how high we could use this power to lift an apple (m=0.20kg) in one minute.arrow_forwardA 75 kg bicyclist is traveling with some speed. She approaches a hill that is 56 m high. How fast must she be biking to make it to the top of the hill and still be moving 1 m/s?arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning