Energy is transferred or transformed from one energy form to another via an energy pathway. In this post, we will briefly discuss the following topics: (a) different forms of energy (b) different mechanisms of energy transformation or conversion or transfer (c) Numerical problems related to energy conversion or transformation with the solution. Here let’s quickly […]

## Solution to problems – class 9 – Set 1 Q36

Problem Statement The mass of sun is 2 × 10^30 kg and the mass of earth is 6 × 10^24 kg. If the average distance between the sun and the earth be 1.5 × 10^8 km, calculate the force of gravitation between them. Solution M1 = mass of the sun = 2 × 1030 kgM2 […]

## 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 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 30

Problem Statement A baseball is popped straight up into the air and has a hang-time of 6 s. Determine the height to which the ball rises before it reaches its peak. (Hint: the time to rise to the max height is one-half the total hang-time.) Solution Hang time = Total time required for upward plus […]

## Solution to problems – class 9 – Set 1 Q 25

Problem Statement A bike accelerates uniformly from rest to a speed of 10 m/s over a distance of 30 m. Determine the acceleration of the bike. Solution U = 0 V = 10 m/s S= 30 m V2 = U2 + 2 a SAs U = 0, the equation becomes: V2 = 2 a SWhich […]

## Solution to problems – class 9 – Set 1 Q 18

Problem Statement A car starts from rest and accelerates uniformly over a time of 7 seconds for a distance of 98 m. Determine the acceleration of the car. Solution Distance travelled: S = ut + ½ a t2 As u = 0, the equation becomes S = ½ at2 so, a = 2S/t2 …..(1) t […]

## Solution to problems – class 9 – Set 1 Q 20

Problem Statement An airplane accelerates down a runway at 4 m/s2 for 30s until is finally lifts off the ground. Determine the distance traveled before takeoff. Solution S = ut + ½ a t2as u = 0, the equation becomes S = ½ a t2 a = 4 m/s2 t = 30 secs So the distance […]

## Solution to problems – class 9 – Set 1 Q 21

Problem Statement A feather is dropped on the moon from a height of 10 meters. The acceleration of gravity on the moon is one sixth of that on the earth. Determine the time for the feather to fall to the surface of the moon. Solution Acceleration of gravity on the moon = 10/6 m/s2 = […]

## Solution to problems – class 9 – Set 1 Q 22

Problem Statement If a rocket-powered sled is accelerated to a speed of 400 m/s in 2 seconds, then what is the acceleration and what is the distance that the sled travels? Solution Acceleration a = (v-u)/t = (400 – 0)/2 = 200 m/s2 Distance travelled by the sled S = ut + ½ a t2 […]

## Solution to problems – class 9 – Set 1 Q 24

Problem Statement Upton Chuck is riding the Giant Drop at Great America. If Upton free falls for 2.60 seconds, what will be his final velocity and how far will he fall? Solution Final velocity V = U + gt Here U = 0, so V = gt = 10 . 2.6 m/s = 26 m/s […]

## Solution of Physics Numericals for class 9 (set 1 Q14)

Problem Statement A body of mass 500 g, initially at rest, is acted upon by a force which causes it to move a distance of 4 m in 2 sec. Calculate the force applied. Solution: mass=m = 500 g = 0.5 kg Initial velocity = u = 0 Distance travelled = s=4 m Time duration […]