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A man throws a tennis ball into the air so that, at the instant when the ball leaves his hand, the ball is 2 m above the ground and is moving vertically upwards with speed 9ms^-1 The motion of the ball is modelled as that of a particle moving freely under gravity and the acceleration due to gravity is modelled as being of constant magnitude 10ms^-2 The ball hits the ground T seconds after leaving the man's hand. Using the model , find the value of T. (4 marks) T= seconds
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9.4.2 Test (CST): Computer-Scored Unit Test Questlon 4 of 25 An electromagnetic wave has a frequency of 3.7 xx10^(18)Hz and a speed of 3xx 10^(8)m//s . Use the equation for wavelength to calculate the wavelength of this wave. A. 8.11 xx10^(-11)m B. 8.31 xx10^(12)m C. 1.11 xx10^(27)m D. 4.51 xx10^(-6)m
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f. State the condition for total internal reflection of light to occur g. State the law of refraction of light h. List the properties of light wave and explain any two of them with the aid of a diagram i. The critical angle for a transparent substance is 39° . Calculate the refractive index.
PHYSICS A catapult used to hold a stone of mass 500g is extended by 20cm with an applied force F . If the stone leaves with a velocity of 40ms^(-1) , the value of F is A. 4.0 xx10^(4)N C. 2.0 xx10^(3)N B. 4.0 xx10^(3)N D. 4.0 xx10^(2)N m+500,=0.5ks e=20cmquadc_(0)=0.2m v=arm-1^(-1) The frictional force is independent of the area of the surfaces in contact. The frictional force depends on the nature of the surfaces in contact. III. The frictional force depends on the speed of sliding. IV. The frictional force is directly proportional to the normal reaction. Which combination of the above is true of sliding friction? A. I, II and IV C. I, III and IV B. I, II and III D. II, III and IV The velocity v of a particle in a time t is given by the equation v=10+2t^(2) Find the instantaneous acceleration after 5 seconds. sqrtv=10+2l^(2) A. 10ms^(-1) B. 15ms^(-1) C. 20ms^(-1) D. 60ms^(-1) sqrt=+0+2xx5^(2) 4. If the force and the velocity on a system are each reduced simultaneously by half, the power of the system is A. Doubled ℓ . Reduced to a quarter B. Constant Đ. Reduced by half 5. The velocity ratio of a machine is 5 and its efficiency is 75% . What effort would be needed to lift a load of 150N with the machine? A. 50N B 40N C. 30N D. 20N