text: Fweigh=mg\nFweigh= 20kg(9.8)\nFweigh= 196N\nFnormal is also 196N\n\nFriction= mu(Fnormal)\nFriction= (.3)(196N)\nFriction= 58.8N\n\nEverytime you see the word "constant speed" or "motionless" that mean all the forces are balanced.\nSo the Friction="horizonal force"\nso 58.8 is the horizonal force that keep the object moving at a constant speed.\n\nwe have to find acceleration.\na=Fnet/m\n\nFfriction is the Fnet because the horizonal force is romoved\na=Friction/m\na= 58.8N/20kg\na= 2.94m/s^2 (should be -2.94m/s^2 because it is slowing down)\n\nVf^2=2ad+Vi^2\n(0m/s)^2=2(-2.94m/s^2)d+(4m/s)^2\n-16m^2/s^2= (-5.88m/s^2)d\nd= 2.72m