SEE Science Notes (What Does It Mean When We Say)

WHAT DOES IT MEAN WHEN WE SAY -

1. The value of gravitational constant (G) is 6.67×10^-11 Nm²/kg²

➤ It means that a force of 6.67×10^-11 N acts between two bodies of mass 1 kg each when they are 1 m apart.

2. The value of acceleration due to gravity (g) is 9.8 m/s²

➤ It means that when a body falls freely towards the earth under the influence of gravity only, its velocity increases by 9.8 m/s every second.

3. The value of gravitational field intensity is 9.8 N/kg

➤ It means that a body of mass 1 kg placed at that point in the gravitational field experiences a force of attraction of 9.8 N.

4. The specific heat capacity of water is 4200 J/kg°C

➤ It means that 4200 J of heat is required to raise the temperature of 1 kg of water by 1 °C.

5. The frequency of AC electricity is 50 Hz

➤ It means that the alternating current completes 50 cycles in one second, i.e. it changes its direction (polarity) 100 times per second.

6. The blood pressure of a human being is 120/80 mm of Hg

➤ It means that the normal systolic pressure is 120 mm of Hg and the normal diastolic pressure is 80 mm of Hg.

7. Meaning of 1 kWh

➤ It is the electrical energy consumed by an appliance of power 1 kW when it runs for 1 hour (1 kWh = 3.6×10⁶ J).

8. Meaning of 1 joule

➤ It is the work done when a force of 1 N moves a body through a distance of 1 m in the direction of the force.

9. Meaning of 1 calorie

➤ It is the amount of heat required to raise the temperature of 1 g of pure water by 1 °C (1 calorie = 4.2 J).

10. Meaning of 1 dioptre

➤ It is the power of a lens whose focal length is 1 m.

11. Meaning of 1 pascal

➤ It means that a force of 1 N is acting normally on an area of 1 m².

12. The current rating of a wire is 5 A

➤ It means that a maximum current of 5 A can be passed through the wire safely.