1. Some 15kg boxes are stacked on top of each other. If each box can withstand 1000N of force before crushing, how many boxes can safely be placed in each stack? 2 A 300kg elevator accelerates up at 4.0m/s'. The force of friction acting on the elevator is 200N. Determine the tension in the cable. 3. A 6.0kg box is being pulled by a rope connected to a 16kg box, which is being pulled by a force of 125N. The force of friction on the 6.0kg box is 20N and the force of friction on the 16kg box in 40N. Determine a The acceleration of the system. b. The tension in the rope between the boxes 4. Find the force of gravitation between two objects with masses 5.0 x 10'*kg and 4.0 x 10 kg respectively, if they are separated by a distance of 200km. 5. If a person weighs 780N on Earth Determine her weight on a planet whose mass is 150 times greater than earth and whose mass is 5 times that of the Earth's. b. What is the acceleration due to gravity on this planet? What is the person's mass on this planet? 6. A go cart starts from rest and accelerates to 30m/s in a distance of 75m. If the force of the engine is 600N and the frictional force is 120N, find the mass of the cart. 7. An applied force of 450N is needed to drag a 100kg crate at a constant speed across a horizontal rough floor. Calculate the coefficient of kinetic friction for the crate on the floor? B. A 2000kg car drives along a road accelerating at 3.1 mrs. Frictional forces of the wind and the road total 1500N. What force must the car's engine exert? 9. How much force is needed to accelerate a 4.0kg block of wood at 6.00m/s' along a rough surface with a coefficient of friction of 0.225? 10. The force of gravitation on a rocket 400km from the centre of the Earth is 900N. What would the force of gravitation on the rocket be when it is 800km from the centre of the Earth