In this post, we will review the formula of Rotational Kinetic Energy and then solve numerical problems based on Rotational Kinetic Energy. Rotational Kinetic Energy formula from the linear kinetic energy formula The equation for linear kinetic energy = KEL = (1/2) m v2 Let’s Convert that equation to its angular analog: KE = (1/2) […]

## Numerical Problems based on combined Gas law or Gas equation & ideal gas equation

In this post, we will solve a few Numerical Problems based on the Combined Gas law (or Gas equation) & the Ideal gas equation. The Formulas used to solve the numerical problems are: PV / T = constant (k) pV = nRT Example 1 A sample of nitrogen occupies a volume of 1.0 L at a […]

## Solution to problems – class 9 – Set 1 Q35

Problem Statement What is the force of gravity on a body of mass 150 kg lying on the surface of the earth ? (Mass of earth = 6 × 10^24 kg; Radius of earth = 6.4 × 10^6 m; G = 6.7 × 10–11 Nm2/kg^2) Solution M1 = mass of the body = 150 kgM2 […]

## Solution to problems – class 9 – Set 1 Q34

Problem Statement Calculate the force of gravitation between two objects of masses 50 kg and 120 kg respectively kept at a distance of 10 m from one another. (Gravitational constant, G = 6.7 × 10 -11 Nm2 /kg^2) Solution M1 = 50 kg M2 = 120 kg Distance = r = 10 m Force of […]

## Solution to problems – class 9 – Set 1 Q31, Q32, Q33

Problem Statement 31) If a box is pushed horizontally on the floor with a force of 10 N and it moves 5 meter along the line of action of the force, then what is the work done by the Gravity or earth’s gravitational pull on that box ? Solution:The angle between gravity and the displacement […]

## Solution to problems – class 9 – Set 1 Q 27

Problem Statement A bullet leaves a rifle with a muzzle velocity of 600 m/s. While accelerating through the barrel of the rifle, the bullet moves a distance of 0.8 m. Determine the acceleration of the bullet (assume a uniform acceleration). Solution Initial velocity of the bullet U=0 Final velocity of the bullet = muzzle velocity […]

## Solution to problems – class 9 – Set 1 Q 26

Problem Statement A race car accelerates uniformly from 25 m/s to 50 m/s in 5 seconds. Determine the acceleration of the car and the distance traveled. Solution Acceleration a = (50-25)/5 a = 5 m/s2 To find out the distance travelled we will use the equation V2 = U2 + 2 a S where S=( […]

## Solution to problems – class 9 – Set 1 Q 29

Problem Statement A plane has a takeoff speed of 100 m/s and requires 1500 m to reach that speed. Determine the acceleration of the plane and the time required to reach this speed. Solution It starts from rest. So initial velocity U = 0 Final velocity = take off velocity = V = 100 m/s […]