English Medium Class 9 - CBSE Question Bank Solutions for Science

A trolley is pushed along a road with a force of 400 N through a distance of 60 m in 1 minute. Calculate the power developed.

A man weighing 500 N carried a load of 100 N up a flight of stairs 4 m high in 5 seconds. What is the power?

An electric heater uses 600 kJ of electrical energy in 5 minutes. Calculate its power rating.

A car of weight 20000 N climbs up a hill at a steady speed of 8 m/s, gaining a height of 120 m is 100 s. Calculate : work done by the car.

A car of weight 20000 N climbs up a hill at a steady speed of 8 m/s, gaining a height of 120 m is 100 s. Calculate : power of engine of car.

Define power. Give the SI unit of power.

A boy weighing 40 kg carries a box weighing 20 kg to the top of a building 15 m high in 25 seconds. Calculate the power. (g = 10 m/s²)

In an experiment to measure his power, a student records the time taken by him in running up a flight of steps on a staircase. Use the following data to calculate the power of the student :

Number of steps = 28
Height of each step = 20 cm
Time taken = 5.4 s
Mass of student = 55 kg
Acceleration = 9.8 m s⁻²
due to gravity

In loading a truck, a man lifts boxes of 100 N each through a height of 1.5 m. (g = 10 m s⁻²)

1. How much work does he do in lifting one box?
2. How much energy is transferred when one box is lifted?
3. If the man lifts 4 boxes per minute, at what power is he working?

In loading a truck, a man lifts boxes of 100 N each through a height of 1.5 m.
How much energy is transferred when one box is lifted?

In loading a truck, a man lifts boxes of 100 N each through a height of 1.5 m.
If the man lifts 4 boxes per minute, at what power is he working?
(g = 10 m s⁻²)

Which one of the following statements about power stations is not true?

An electric motor raises a load of 0.2 kg, at a constant speed, through a vertical distance of 3.0 m in 2 s. If the acceleration of free fall is 10 m/s², the power in W developed by the motor in raising the load is :

What is meant by atomicity ? Explain with two examples.

What is the atomicity of the following ?

1. Oxygen
2. Ozone
3. Neon
4. Sulphur
5. Phosphorus
6. Sodium

Write the formulae of the following compounds. Also name the elements present in them.

1. Water
2. Ammonia
3. Methane
4. Sulphur dioxide
5. Ethanol

In what form does oxygen gas occur in nature ?

In what form do noble gases occur in nature?

What do the following denote ?

1. N
2. 2N
3. N₂
4. 2N₂