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Short answer type of questions/HOTS:
Calculate the pressure if 300N force is exerted on the box and the area of contact is 100 cm2. Solution
Area= 100 cm2 or 100/10000 m2 = 0.01 m2
Pressure= 300/0.01 N/m2
Pressure= 30000 N/m2 or Pa
If 200N force exerted on the top of the box and area of contact is 5 m2. Calculate the pressure. Solution
Area= 5 m2
Pressure= 200/5 N/m2
Pressure= 40 N/m2 or Pa
How can a force effect the objects? Solution
Force effects the objects in the following ways: -
(i)Force can move stationary objects.
(ii)Force has a tendency to change the speed of moving object.
(iii)Force can be applied to stop a moving object.
(iv)Force can change the direction of moving body.
(v)Force can change the shape of substance.
Do machines produce force on their own. What type of force produced by machines? Solution
Machines do not produce force on their own. They require energy to produce force. The force produced by machines is called mechanical force.
Write any three applications of pressure. Solution
The three applications of pressure are as follows: -
(i)The sharp pointed objects like iron nails have less area of contact therefore, they can penetrate the surface of materials such as wood, clothes and papers etc.
(ii)High-rise buildings are built rectangular or square-shaped with wide surface area covering so, they exert less pressure on the ground. If they build narrow, they fall and cannot sustain longer.
(iii)School bags have wide straps because they exert less pressure on the shoulders.
What is the “Magdeburg Experiment”? Solution
The Magdeburg Experiment was a famous experiment performed by Otto von Guericke in 1657. This experiment was performed to reveal the concept of atmospheric pressure. He demonstrated the experiment with his vacuum pump that he created with two identical metallic hemispheres with smooth edges.
The altimeter is a device that is used to measure the change in pressure with height accurately. It provides the accurate distance of the aircraft from the ground.
Long answer type questions:
What is a barometer. Draw a well-labelled diagram of a barometer. Explain the implications of atmospheric pressure. Solution
A device that is used to measure the atmospheric pressure. It is a narrow, thick-glass tube, one-metre long and sealed at one end. The basic principle of a barometer to balance the vertical column of mercury by using atmospheric pressure.
The following implications of atmospheric pressure are given below: -
(i)Astronauts wear spacesuit because there is no atmosphere in the space.
(ii)At high altitude, the atmospheric pressure decreases. Therefore, people who climb the pinnacle of mountain suffer with nose bleeding cause due to the higher body pressure. The blood pops out from the capillaries.
(iii)Ink pens start leaking at higher altitude as the atmospheric pressure decreases above the sea level.
What is manometer? Draw a diagram of manometer. Explain the implications of liquid pressure. Solution
Manometer is a device that is used to measure the liquid pressure. This device is made up of U-shaped transparent glass tube which has two glass two ends: one is free and another is attached to a rubber.
The implications of liquid pressure are: -
(i)The bottom of dams is constructed thicker than their top to withstand a large liquid pressure.
(ii)Sea divers wear specially designed suits to withstand enormous liquid pressure at great depth.
(iii)The hulls of submarines are created strongly to withstand a great amount liquid pressure at depth.
This Force and Pressure Extra questions for Class 8 is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.