BAF Shaheen College Dhaka Practice Pre-test Examination 2020
Class-Ten (English Version) Subject: Physics (Creative)
Subject Code: 0136
Time: 2Hrs 30 Min Full Marks – 50
[ Answer any five of the following questions]
1. A cycle started to move along a straight road with the initial velocity of 5 ms-1 and with acceleration 1.5 ms-2. At the same time a Motorcycle from 70m behind started to move along the same road from rest with the acceleration of 2 ms-2 .
a) Define average velocity. 1
b)Why does a person sitting in a car at rest lean in the backward direction when the car starts moving? 2 c)What will be the distance between the cycle and the motor cycle after 7 seconds? 3
d) Is it possible for the motor cycle to cross the cycle?- Verify mathematically. 4
2. A ball of mass 50 gm was thrown horizontally with the velocity of 55 m/s. a)Define Momentum. 1
b) What is the physical meaning of Momentum? 2
c) With the same velocity if it is projected in the vertically upward direction when its kinetic energy will be its initial kinetic energy? 3
d)Verify mathematically whether a force 10 N can stop the ball at a distance of 5 metre. 4
3. An Object of mass 3.5 kg was released in water and it was floating being immersed. Then theobject was released in a liquid of density 600kgm-3. The density of water is 1000 kgm-3. a)What is Buoyancy? 1
b) Explain the conditions for an object for floating and sinking in a liquid. 2
c) Calculate the volume of the object. 3
d)What is the weight of the object in the above mentioned liquid. 4
4. An Electric Motor of power 12 kw can lift 800 kg of water to a height of 25m in 20 seconds. a) Write down the third law of falling body. 1
b) Convert 12 Kwh into Joule. 2
c) Calculate the Efficiency of the Motor. 3
d) Had the Efficiency been 75% then what would be the difference between the used energy?- Explain mathematically. 4
5. The distance between two charges +35C and -20C in two conductors of equal size is 30cm. a) Define Electric potential. 1
b) What do you understand by ‘ 220 Volt-60 Watt’ written on the body of an electric bulb? 2
c) If the two charges are connected by a conducting wire for a short while then what will be the change of force and nature of force between them? 3
d) If a charge of +5C is placed between them where the Electric Intensity will be zero?- Explain mathematically. 4
6. The distance between the source and reflector is 20m. At that time the temperature of air is 200C.
a) What is called Intensity of sound? 1
b) Why sound is a type of wave? 2
c) What time is required for the sound to travel from the source to the reflector? 3 d) Verify mathematically whether echo will be heard or not at the temperature of 300C. 4
7. A object of length 7.5 cm was placed at a distance of 25 cm from a concave mirror of radius of curvature 100 cm.
a) Define mirror. 1
b) Why a minimum distance is required to hear an echo? 2
c) Calculate the distance of the image. 3
d) Draw the image of the object and find the position, size and nature of the image. 4
8. The ratio of the number of turns of the primary and secondary coil of a transformer is 1: 50.
The electric current and voltage of the primary coil are 5A and 220V respectively.
a) What is an Electric Motor? 1
b) Why an AC voltage is used in the primary coil of a Transformer? 2 c) Find the ratio of the voltage in the primary coil and the voltage in the secondary coil. 3 d) Prove that the power in the Primary coil is equal to the power in the secondary coil. 4
