Solution:Mass of the object, m = 12 kg,potential energy, Ep = 480 J.Ep = mgh480 J = 12 kg × 10 m s–2 × hh = 480 J / 120 kg m s –2 = 4 m.The object is at the height of 4 m.
Solution:(i) Power expended by girl A:Weight of the girl, mg = 400 NDisplacement (height), h = 8 m Time taken, t = 20 sPower, P = Work done / time taken Power = mgh / t P = 400 N × 8 m / 20 s= 160 W. (ii) Power expended by girl B:Weight of …
Solution:Power of electric bulb = 60 W= 0.06 kW.Time used, t = 6 hEnergy = power × time taken= 0.06 kW × 6 h= 0.36 kW h= 0.36 ‘units’.The energy consumed by the bulb is 0.36 ‘units’.
Solution:Weight of the boy,w = mg = 50 kg × 10 m s–2 = 500 NHeight of the staircase,h = 45 × 15/100 m = 6.75 mTime taken to climb, t = 9 s, power, P = Work done/time taken mgh / t Power (P) = (500 N × 6.75 m ) / 9s= 375 …
COMMERCIAL UNIT OF ENERGY The unit joule is too small and hence is inconvenient to express large quantities of energy. We use a bigger unit of energy called kilowatt hour (kW h). kWh = (Watt x hour ) / 1000 What is 1 kW h? Let us say we have a machine that uses 1000 …
Definition “Power is defined as the rate of doing work or the rate of transfer of energy.“ If an agent does a work W in time t, then power is given by:Power = work/time or P =w / t The S I unit of power is J s–1 = kg m2s-3 = watt (W) [in …
According to this law,“energy can only be converted from one form to another; it can neither be created or destroyed. The total energy before and after the transformation remains the same.” The law of conservation of energy is valid in all situations and for all kinds of transformations. Consider a simple example. Let an object …
Energy is a scalar quantity whose SI unit is the joule (J). Energy is found in many things and thus there are different types of energy. All forms of energy are either kinetic or potential. Kinetic EnergyThe energy in motion is known as Kinetic Energy. For example, a moving ball, flowing water etc. The SI …
What is Energy ? The capacity to do work is energy. Energy can only be changed from one form to another; it cannot be created or destroyed. Energy is measured in the same manner as work, i.e. Joules. There are various types of energy because it is present in many different things. There are two …
