1 Watt is equal to
1 Js-1
Watt Definition: Understanding the Unit of Power
The question asks to identify what 1 Watt is equal to. To answer this, we need to understand the fundamental definition of a Watt in physics.
The Watt (W) is the standard International System of Units (SI) unit of power. Power is defined as the rate at which work is done or energy is transferred. In simpler terms, it measures how quickly energy is used or produced.
Power Formula and Units
The formula for power ($P$) is given by:
\[ P = \frac{\text{Work Done (or Energy Transferred)}}{\text{Time Taken}} \]
In terms of SI units:
- The SI unit of Work or Energy is the Joule (J).
- The SI unit of Time is the second (s).
Therefore, substituting these units into the power formula, we get the unit of power:
\[ \text{Unit of Power} = \frac{\text{Joule}}{\text{second}} \]
This can be written as Joule per second, or more concisely in scientific notation as $\text{J s}^{-1}$.
By definition, 1 Watt is equivalent to 1 Joule per second.
\[ 1 \text{ Watt} = 1 \text{ J s}^{-1} \]
Analyzing the Options
Let's evaluate each given option based on this definition of Watt:
- Option 1: 10 Js-1
This option suggests 10 Joules per second. While $\text{J s}^{-1}$ is the correct unit for Watt, the magnitude "10" is incorrect. 1 Watt is specifically 1 Joule per second, not 10. - Option 2: 1 Js
This option represents "1 Joule second." This means Joule multiplied by second, which is a unit of action or angular momentum, not power. Power is energy per unit time, not energy times time. Therefore, this is incorrect. - Option 3: 1 Js-1
This option represents "1 Joule per second." As derived from the definition of power (Work/Energy per unit Time), this unit directly corresponds to 1 Watt. This is the correct definition. - Option 4: 10 Js
This option combines the incorrect magnitude "10" with the incorrect unit "Js" (Joule times second). Both parts of this option are incorrect for defining 1 Watt.
Based on the analysis, the only option that correctly defines 1 Watt in terms of Joules and seconds is 1 Js-1.
Important Questions from Miscellaneous
A stone is thrown horizontally from the top of a 20 m high building with a speed of 12 m/s. It hits the ground at a distance R from the building. Taking g = 10 m/s2 and neglecting air resistance will give :
A sphere of volume V is made of a material with lower density than water. While on Earth, it floats on water with its volume f1V (f1 < 1) submerged. On the other hand, on a spaceship accelerating with acceleration a < g (g is the acceleration due to gravity on Earth) in outer space, its submerged volume in water is f2V. Then:
A railway wagon (open at the top) of mass M1 is moving with speed v1 along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes M2 and speed becomes v2. Taking the rain to be falling vertically and the water stationery inside the wagon, the relation between the two speeds v1 and v2 is :
Consider the following statements:
1. Distance between the longitudes becomes zero on North Pole and South Pole.
2. Distance between the longitudes is maximum on the Equator.
3. Number of longitudes is more than number of latitudes.
Which of the statements given above is/are correct?
One block of 2⋅0 kg mass is placed on top of another block of 3⋅0 kg mass. The coefficient of static friction between the two blocks is 0⋅2. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as 10 m/s2, the maximum value of the frictional force is :
