Physics: Questions and Answers

Tutorial -1 1. Round off the following number to three significant figures a) 4.65735 m b) 55.578 s c) 4555 N d) 2768 kg Ans: 4.66 m, 55.6 s, 4.56 kN, 2.77 Mg 2. Represent each of the following quantities in the correct SI form using an appropriate prefix: c) 0.00532 km a) 0.000431 kg b) 35.3 (103) N Ans: 0.431 g, 35.3 kN, 5.32 m 3. Evaluate each of the following and express with an appropriate prefix: a) 354 mg (45 km) / (0.0356 kN) b) (0.00453 Mg)(201 ms) c) 435 MN / 23.2 mm Ans: 0.447 kg.m/N, 0.911 kg.s, 18.8 GN/m 4. What is the weight in newtons of an object that has a mass of: (a) 10 kg b) 0.5 g c) 4.50 Mg? Express the result to three significant figures. Use an appropriate prefix. Ans: 98.1 N, 4.90 mN, 44.1 kN 5. Two particles have a mass of 8 kg and 12 kg respectively. If the distance between them is 800mm, determine the force of gravity acting between them. Compare this result with the weight of each particle. Ans: 10 nN, 78.5 N, 118 N 6. Determine the mass of an object that has a weight of a) 20mN b) 150 kN c) 60 MN. Express the answer to three significant figures. Ans: 2.04 g, 15.3 Mg, 6.12 Gg 7. Using the base unit of the SI system, show that F = Gm1m2/r2 is a homogenous equation which gives F in Newton. Determine to three significant figures the gravitational force acting between two particles. The mass of each particles is 200 kg and distance between is 600 mm. Ans: 7.41 µN