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.
ScanSolve AI Answer
Here's the solution for Item 2, part a): Step 1: Convert all given values to SI units. The mass of weed (m) is 30 tonnes. m = 30 tonnes = 30 × 1000 kg = 30000 kg The input power (P_in) of the machine is 20 kW. P_in = 20 kW = 20 × 1000 W = 20000 W The time (t) taken is 5 minutes. t = 5 minutes = 5 × 60 s = 300 s The height (h) the weed is lifted is 15 m. h = 15 m We use the acceleration due to gravity (g) as 9.81 m/s^2. Step 2: Calculate the useful work done (W) by the machine. The useful work done is the potential energy gained by lifting the weed. W = mgh W = 30000 kg × 9.81 m/s^2 × 15 m W = 4414500 J Step 3: Calculate the useful output power (P_out) of the machine. Output power is the useful work done per unit time. P_out = (W)/(t) P_out = 4414500 J300 s P_out = 14715 W Step 4: Determine the efficiency () of the machine. Efficiency is the ratio of output power to input power, expressed as a percentage. = P_outP_in × 100\% = 14715 W20000 W × 100\% = 0.73575 × 100\% = 73.575\% Rounding to one decimal place: ≈ 73.6\% The efficiency of the machine is 73.6%. That's 2 down. 3 left today — send the next one.