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A student finds some information about energy-saving light bulbs. (a) A 30W light bulb uses 600J of electrical energy in a certain period of time . In that time, it produces 450 J of light energy. The rest of the energy is wasted. (i) Calculate the energy wasted by the light bulb in this period of time. __ Wasted energy= __ J (1)
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MoreAnswer ALL questions. Write your answers in the spaces provided. Some questions must be answered with a cross in a box 凶 . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross ⊠ . 1 (a) State three differences between radio waves and sound waves. (3) 1 2 3
The diagram shows a prism placed on a horizontal floor. The prism has height 5m The volume of the prism is 30m^(3) The pressure on the floor due to the prism is 55 newtons //m^(2) Work out the force exerted by the prism on the floor.
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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
09.3.A Questions - Conservation of momentum Name. Testing conservation of momentum 1 During a game of tennis a ball of mass 0.052kg is thrown up vertically and then hit with a tennis racquet. Its horizontal velocity immediately after the serve is 250kmh^(-1) . a What is the horizontal velocity of the ball in ms^(-1) ? 250 xx1000-:60^(2)=69.4ms^(-1) 69ms^(-1) b Calculate the horizontal momentum of the ball immediately after it is served. (1 mark) 0.052 xx69=5.0kyms^(-1) (1 mark) c The racquet and ball are in contact for 0.08s . Calculate the net force acting on the ball due to the racquet. (2 marks)
A piece of cheese has a mass of 232g and a density of 1.6g//cm^(3) . Calculate the volume of the cheese.
A satellite travelled at a speed of 7473 metres per second for 2872 seconds. Use a calculator and the formula below to calculate the distance that the satellite travelled during this time. Give your answer in metres (m) to 3 s.f.
A watering can holds 0.00031m^(3) of water. What is this volume in mm^(3) ?
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