1.7.4. Power
A subsection of Physics, 0625, through 1. Motion, forces and energy
Listing 10 of 51 questions
Use A student wishes to work out how much power she uses to lift her body when climbing a flight of stairs. Her body mass is 60 kg and the vertical height of the stairs is 3.0 m. She takes 12 s to walk up the stairs. Calculate the work done in raising her body mass as she climbs the stairs, work = the output power she develops when raising her body mass. power = At the top of the stairs she has gravitational potential energy. Describe the energy transformations taking place as she walks back down the stairs and stops at the bottom.
0625_s07_qp_3
THEORY
2007
Paper 3, Variant 0
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Some builders decide to measure their personal power ratings using apparatus they already have on site. shows the arrangement they use. pulley rope load pulley In the table below, list the three quantities they must measure in order to calculate one man’s power, and the instrument they would use for each measurement. quantity to be measured instrument used for measurement 1. 2. 3. One workman is measured as having a power of 528 W. His weight is 800 N. He can develop the same power climbing a ladder, whose rungs are 30 cm apart. How many rungs can he climb in 5 s? number of rungs = The human body is only about 15% efficient when climbing ladders. Calculate the actual energy used from the body of the workman in when he climbs 20 rungs. energy used =
0625_s11_qp_31
THEORY
2011
Paper 3, Variant 1
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Questions Discovered
51