This physics problem tests your understanding of fundamental physical laws and their applications. The step-by-step solution below breaks down the problem using relevant equations and physical reasoning.
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Welcome back Small — been a while! Let's pick up where you left off. a) i) The work done in moving the bag from A to B Step 1: Identify the given values for applied force and distance. Applied force F = 250 N Distance d = 10 m Step 2: Calculate the work done using the formula W = F × d. W_in = 250 N × 10 m = 2500 J The work done in moving the bag from A to B is 2500 J. ii) The useful work done Step 1: Identify the given values for mass, height, and acceleration due to gravity. Mass m = 50 kg Height h = 4 m Acceleration due to gravity g = 9.8 m/s^2 Step 2: Calculate the useful work done (potential energy gained) using the formula W = mgh. W_out = 50 kg × 9.8 m/s^2 × 4 m = 1960 J The useful work done is 1960 J. iii) What is the efficiency of the arrangement? Step 1: Use the calculated work input (W_in) and useful work output (W_out). W_in = 2500 J W_out = 1960 J Step 2: Calculate the efficiency using the formula = W_outW_in × 100\%. = 1960 J2500 J × 100\% = 0.784 × 100\% = 78.4\% The efficiency of the arrangement is 78.4\%. iv) Give one reason why the efficiency is less than 100% Efficiency is less than 100% due to friction between the bag and the inclined plane, which converts some of the input energy into heat. b) i) The change in the kinetic energy Step 1: Identify the given values for mass and speeds. Mass m = 1000 kg Initial speed u = 20 m/s Final speed v = 3 × 20 m/s = 60 m/s Step 2: Calculate the initial kinetic energy (KE_i). KE_i = (1)/(2)mu^2 = (1)/(2) × 1000 kg × (20 m/s)^2 = 500 kg × 400 m^2/s^2 = 200000 J Step 3: Calculate the final kinetic energy (KE_f). KE_f = (1)/(2)mv^2 = (1)/(2) × 1000 kg × (60 m/s)^2 = 500 kg × 3600 m^2/s^2 = 1800000 J Step 4: Calculate the change in kinetic energy ( KE). KE = KE_f - KE_i = 1800000 J - 200000 J = 1600000 J The change in the kinetic energy is 1600000 J. ii) The power developed Step 1: Use the calculated change in kinetic energy and the given time. KE = 1600000 J Time t = 14.5 s Step 2: Calculate the power developed using the formula P = ( KE)/(t). P = 1600000 J14.5 s ≈ 110344.83 W The power developed is approximately 110344.83 W. c) Alternative energy sources to fossil fuels include sun, wind. For each source, give an example of how energy may be obtained from it. • Sun: Energy is obtained from the sun by using solar panels (photovoltaic cells) to convert sunlight directly into electricity, or by using solar thermal collectors to heat water. • Wind: Energy is obtained from wind by using wind turbines to convert the kinetic energy of moving air into rotational energy, which then drives a generator to produce electricity. d) Identify the safety symbols A and B in figure 6. Figure 6 is not provided in the image. Send me the next one 📸