ame: 21. Christy, of the stadium (9m). how fast is it going when it hits the Rac

Question

ame: 21. Christy, of the stadium (9m). how fast is it going when it hits the Rachael and Rebecca drop a weight from the top ground a. 6.64 m/s c, 3.28 m/s lb. 176.4 m/s d. 9.39 m/s At point 4 the energy levels are c. 25%PE, 75% KE a. 100% PE, 0%KE. d, 75% PE, 25% KE b, 50% PE, 50% KE 23. In order for work to be done c, the force must be in the direction of a. there must be a foce applied d. all of the above b. there must be movement 24. An iron sphere of mass 30 kg has the same diameter as an aluminium sphere whose mass is 10.5 kg. The spheres are dropped simultaneously from a cliff. When they are 10 m from the ground, they have the same c. potential energy a, acceleration kinetic energy 25. As a light wave meets a boundary between two mediums, it slightly bends at some angle. This is a definition c, interference a. reflection d. refraction b. diffraction

Explanation / Answer

(21) mgh = 0.5*m*v^2

=> v^2 = 2gh = 2*9.81*9

=> v = 13.29 m/s

So, (c) is the correct answer.

(22) From the diagram, it is clear that at point '4' , there is 25% P.E. and 75% K.E.

So, option (c) is the correct answer.

(23) All of the options are correct for the work done.

So, option (d) is the correct answer.

(24) Potential and kinetic energy shall be different because these two depends on mass.

Acceleration is only the gravitational acceleration which is equal to 9.81 m/s^2, same for the both masses.

So, option (a) is the correct answer.

(25) This is called refraction.

option (d) is the correct answer.

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