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Questions in physics

[Done] 8. Ball bearings are used to a. give a streamlined shape b. increase grip c. increase drag d. reduce friction Write T for True and F for False statements. Correct the false statement/s. 1. Frictional force between two surfaces depends on the nature of the two surfaces. 2. Rolling friction is greater than sliding friction. 3. Ball bearings are used to increase friction. 4. Fluid friction acts between two moving solid surfaces in contact with each other. 5. Tyres of vehicles have treads to reduce speed. Short answer type questions Answer the following. 1. Give an example of contact force. 2. What is the SI unit of force? 3. What is a spring balance used for? 4. Give an example of non-contact force. 5. Give two advantages of friction.

[Done] Which best describes a force? A. a vector with magnitude and direction B. a vector with speed and strength C. a vector with direction only D. a vector with strength only

[Done] A sphere of radius [tex]$r$[/tex] is moving at speed [tex]$v$[/tex] through air of density [tex]$\rho$[/tex]. The resistive force [tex]$F$[/tex] acting on the sphere is given by the expression [tex]$F=B r^2 \rho v^k$[/tex] where [tex]$B$[/tex] and [tex]$k$[/tex] are constants without units. i. State the SI base units of [tex]$F, \rho$[/tex] and [tex]$v$[/tex]. ii. Use base units to determine the value of [tex]$k$[/tex].

[Done] The volume of iron will have the same thermal capacity as 1200 cal/°C of water if 16 × 10^x cc, x value is ......... (specific heat of iron = 0.1 cal/g°C, density of iron = 7.5 g/cc)

[Done] Describe the correct method for measuring the length of an object if the zero mark on your measuring scale is not visible. Provide an example.

[Done] *Please include a label for your answers! 1. Calculate the wave speed (in m/s) for the following waves: a) A sound wave in steel with a frequency of 500 Hz and a wavelength of 3.0 meters. (2pts)

[Done] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Done] 1. Which of the following devices use the principle of reflection? a) Microscope b) Periscope c) Telescope d) Both b and c 2. Assertion (A): Copper is widely used in electrical appliances

[Done] Select the correct answer. Object A attracts object B with a gravitational force of 5 newtons from a given distance. If the distance between the two objects is reduced in half, what will be the changed force of attraction between them? A. 2.5 newtons B. 10 newtons C. 15 newtons D. 20 newtons E. 25 newtons

[Done] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?