Calculate the cost of using a 2kW immersion rod for heating water in a house for one hour each day for 60 days if the rate is Rs. 1.50 per unit kWh.
What is the Difference between Power and Energy?
Does force of friction do positive, negative or zero work? Important
An engine does 54,000 J work by exerting a force of 6000 N on it. What is displacement by force Important
A moving body of 30 kg has 60 J of KE. Calculate the speed.
Numerical for finding electricity cost Important You are here
Calculate the work done by heart for each beat. Important
Activity 11.15 - An object of mass 20 kg is dropped from a height of 4 m Important
Last updated at May 29, 2023 by Teachoo
Extra Questions 3 Calculate the cost of using a 2kW immersion rod for heating water in a house for one hour each day for 60 days if the rate is Rs. 1.50 per unit kWh. Power of the rod = 2 kW Time taken in 1 day = 1 hour Time taken in 60 days = 1 × 60 = 60 hours Let’s first find the energy consumed Power = (𝐸𝑛𝑒𝑟𝑔𝑦 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑)/(𝑇𝑖𝑚𝑒 𝑡𝑎𝑘𝑒𝑛) Energy consumed = Power × Time Energy consumed = 2 × 60 Energy consumed = 120 kWh Finding cost Cost of 1 kWh = Rs 1.50 Cost of 120 kWh = 120 × 1.50 = 120 × 150/100 = 12 × 15 = Rs 180 The total cost is Rs 180 Extra Questions 4 The power of a heart which beats 72 times in a minute is 1.2kW. Calculate the work done by heart for each beat. Power of the heart = 1.2 kW = 1.2 × 1000 W = 1200 W Time taken = 1 minute = 60 seconds We know that Power = (𝑊𝑜𝑟𝑘 𝑑𝑜𝑛𝑒)/(𝑇𝑖𝑚𝑒 𝑡𝑎𝑘𝑒𝑛) Work done = Power × Time = 1200 × 60 = 72000 J Now, Work done to beat 72 times = 72000 J Work done to beat 1 times = 72000/72 = 1000 J = 1000/1000 kJ = 1 kJ Work done to produce 1 heart beat is 1 kJ