Class 9 – Physics – worksheet –thrust & pressure

ARMY PUBLIC SCHOOL, GOLCONDA

Class 9 – Physics – Ch 10 – FLOTATION

(WORKSHEET)

Q & A’s

         1.  Define thrust. What is its unit?

         2.  Define pressure. What is the S.I unit for pressure?

         3.  State the two factors on which pressure depends. Show with the help of formula.                   State one example showing effect of area on pressure.

         4.  Calculate the pressure when a force of 200 N is exerted on an area of –

                 a.)  10 cm²

                 b.)   5  m^2.  

         5.  How much thrust and pressure a man of weigh 80 Kg exert on the ground if-

                 a.)  He is standing with one foot.

                 b.)  He is standing on both feet.

                 c.)  He is lying.

                GIVEN THAT area of man’s body is 0.6 m²  and area of a foot is 80 cm² .

         6.  Pressure exerted by cubical box of side 4 cm on the surface is 10 Pa. what is the                     weight and mass of the block. (Use, g = 10 m/s²).

         7.  A pressure of 150 Pa acts on an area of 15 m². What is the force acting on the                           area? What force will be exerted by the application of same pressure if the area is                   made one-fifth?

         8.  When the pressure on the ground is more – when a man is walking or when a man                  is standing? Explain.

           

         9.  A rectangular wooden block has length, breadth and height of 25 cm, 5 cm and 15                   cm, respectively. This wooden block is kept on the ground in three different ways,                   turn by turn. Which of the following is the correct statement about the pressure                       exerted by this block on the ground? Explain why?

              a.)  The maximum pressure is exerted when the length and breadth form the                          base.

             b.)  The maximum pressure is exerted when the length and height form the base.

             c.)  The maximum pressure is exerted when the breadth and height form the base.

             d.)  The minimum pressure is exerted when the length and breadth form the base.

        10.  An elephant weighing 100,000 N stands on one foot of area 5000 cm² whereas a                       girl weighing 500 N is standing on one ‘stiletto’ heel of area 5 cm²

                                            

             a.)  Which of the two, elephant or girl, exerts a larger force on the ground?

             b.)  What pressure is exerted on the ground by the elephant standing on one foot?

             c.)  What pressure is exerted on the ground by the girl standing on one heel?

             d.)  Which of the two, elephant or girl, exerts a larger pressure on the ground?

             e.)  What is the ratio of the pressure exerted by the girl to the pressure exerted by                the elephant?