(English Medium) ICSE Class 9 - CISCE Question Bank Solutions

A train starts from rest and accelerates uniformly at a rate of 2 m s⁻² for 10 s. It then maintains a constant speed for 200 s. The brakes are then applied and the train is uniformly retarded and comes to rest in 50 s. Find

1. The maximum velocity reached,
2. The retardation in the last 50 s,
3. The total distance travelled,
4. The average velocity of the train.

A space craft flying in a straight course with velocity of 75 km s^-1 fires its rocket motors for 6.0 s. At the end of this time its speed is 120 km s^-1 in the same direction.

Find

(i) The space craft's average acceleration while the motors were firing

(ii) The distance travelled by the space craft in the first 10 s after the rocket motors were started, the motors being in action for only 6 s.

A car travels with uniform velocity of 25 m s^-1 for 5 s. The brakes are then applied and the car is uniformly retarded and comes to rest in further 10 s. Find:

1. The distance which the car travels before the brakes are applied,
2. Retardation and
3. The distance travelled by car after applying the brakes.

A vehicle is accelerating on a straight road. Its velocity at any instant is 30 km/h. After 2 s, it is 33.6 km/h, and after further 2 s, it is 37.2 km/h. Find the acceleration of the vehicle in m s^-2. Is the acceleration uniform?

A body of volume V and density ρ is kept completely immersed in a liquid of density ρ_L. If g is the acceleration due to gravity, then write expressions for the following:

(i) The weight of the body, (ii) The upthrust on the body,

(iii) The apparent weight of the body in liquid, (iv) The loss in weight of the body. 

A sphere of iron and another sphere of wood of the same radius are held under water. Compare the upthrust on the two spheres.

[Hint: Both have equal volume inside the water].

A sphere of iron and another of wood, both of same radius are placed on the surface of water. State which of the two will sink? Give a reason for your answer. 

How does the density of material of a body determine whether it will float or sink in water? 

A solid of density 5000 kg m^-3 weighs 0.5 kgf in air. It is completely immersed in water of density 1000 kg m^-3. Calculate the apparent weight of the solid in water. 

A metal cube of edge 5 cm and density 9 g cm^-3 is suspended by a thread so as to be completely immersed in a liquid of density 1.2 g cm^-3. Find the tension in thread. (Take g = 10 m s^-2) 

How are the (i) Mass, (ii) Volume and (iii) Density of a metallic piece affected, if at all, with an increase in temperature?

Complete the following sentence.

S.I. unit of density is .......... .

Complete the following sentence.

Density in kg m^-3 =  ............ × density in g cm^-3

A body weighs W₁gf in air and when immersed in a liquid it weighs W₂gf, while it weights W₃gf on immersing it in water. Find:

1. volume of the body
2. upthrust due to liquid
3. relative density of the solid
4. relative density of the liquid

Relative density of a substance is expressed by comparing the density of that substance with the density of : 

The unit of relative density is :