
Kinematics, Dynamics, Mass Weight and Density Question1. It takes 10 minutes for a MRT train to travel 7.0 km from the Tanah Merah MRT Station to the Changi airport. Analysis: 2. Darren has recently taken up snowboarding as a hobby. He is practising making smooth turns while travelling up sloped inclines. The velocitytime graph in Figure shows his motion travelling up an embankment and partway down. (a)(i) Comment: A very common mistake is to simply read the value of speed at t = 8.0s as 6.0m/s, and then divide it by 8.0 to get the answer as acceleration of 6/8 = 0.75ms^{2} 3. A boy applies a force of F to push an object which is placed on a surface. The force R is the reaction force according to Newton’s Third Law of Motion. Analysis: 4. Ryan is pulling a block with a rope across a floor. The block has a mass of 10.0 kg. Ryan pulls with a horizontal force of 60.0 N and the constant force of friction is 20.0N. (a) F_{net} = F_{applied}  frictional force 5. A spaceship descends vertically toward the surface of the Moon with a constant speed of 3.0 m/s. The total mass of the spaceship is 15.0 kg. Assume the gravitational strength on the Moon to be 1.6 N/kg. During the first part of the descent, the upward force acting on the space ship is 24.0 N. (a) Note that g is 1.6N/kg now! 6. Block A, B and C has a mass of 4.0 kg, 12.0 kg and 13.0 kg respectively as shown in Figure. They are connected by light ropes and the ropes pass over frictionless and massless pulleys. The block B is on the rough horizontal surface. (a) The block B will move to the right because the pulling force from block C is greater than that from block A since block C is heavier.
7. A large wrecking ball is held in place by two light steel cables as shown in Figure. Given the weight of the wrecking ball is 400 N, calculate the tension TA and TB in the cables by the means of a scale diagram. Analysis: 8. Two liquids X and Y were mixed together. The mass of liquid X is 0.40 kg and its density is 2.0 gcm^{3}. The mass of liquid Y is 0.26 kg and its density is 65.0 gcm^{3}. Assume that no new substance is produced by the mixing, determine (a) Recall density = mass / volume 
