An electric heater is rated 1500 W. How much energy does it use in 10 hours?
Solution and Explanation
Electric heater’s power \(p = 1500\ W = 1.5\ kW\)
Energy = power × time
Energy = \(1.5\ kW × 10\ h \)
Energy = \(15\ kWh\)
Top Questions on Energy
- Which one of the following is widely used as fuel to produce nuclear energy?
- Match List-I with List-II:
- During the process of conversion from liquid to solid, the internal energy of the water
- Two sources of non-conventional energy
- A steel ball of mass 200 g falls freely from a height of 20 m and bounces to a height of 10.8 m from the ground. If the energy lost in this process is absorbed by the ball, the rise in its temperature is:
Questions Asked in CBSE Class IX exam
- “To hear any flute is to be drawn into the commonality of all mankind.” Why does the author say this?
- CBSE Class IX
- Kathmandu
A driver of a car travelling at \(52\) \(km \;h^{–1}\) applies the brakes Shade the area on the graph that represents the distance travelled by the car during the period.
Which part of the graph represents uniform motion of the car?- CBSE Class IX
- Graphical Representation of Motion
- Match the phrases in Column A with their meanings in Column B.
A B (i) broke out (a) an attitude of kindness, a readiness to give freely (ii) in accordance with (b) was not able to tolerate (iii) a helping hand (c) began suddenly in a violent way (iv) could not stomach (d) assistance (v) generosity of spirit (e) persons with power to make decisions (vi) figures of authority (f) according to a particular rule, principle, or system - CBSE Class IX
- My childhood
ABC is a triangle in which altitudes BE and CF to sides AC and AB are equal (see Fig). Show that
(i) ∆ ABE ≅ ∆ ACF
(ii) AB = AC, i.e., ABC is an isosceles triangle.
- CBSE Class IX
- Some Properties of a Triangle
- The author speaks both of people who were very aware of the differences among them and those who tried to bridge these differences. Can you identify such people in the text?
- CBSE Class IX
- My childhood
Concepts Used:
Work-Energy Theorem
The work and kinetic energy principle (also known as the work-energy theorem) asserts that the work done by all forces acting on a particle equals the change in the particle's kinetic energy. By defining the work of the torque and rotational kinetic energy, this definition can be extended to rigid bodies.
The change in kinetic energy KE is equal to the work W done by the net force on a particle is given by,
W = ΔKE = ½ mv2f − ½ mv2i
Where,
vi → Speeds of the particle before the application of force
vf → Speeds of the particle after the application of force
m → Particle’s mass
Note: Energy and Momentum are related by, E = p2 / 2m.