One way to do this is to shake the bottle downwards very hard: this causes the ketchup to exert the initial downward force needed to make the bottom of the bottle exert force back onto the ketchup to unstick the ketchup.
Let m0 = (the original mass of the block). Then the mass of the block is tripled, so the final mass is mf = 3m0. This happens while a constant net force is applied to the block, so F = constant. Using Newton’s 2nd law, F = ma. For the original block, we have
F0= m0 a0.(The original force is equal to the original mass times the original acceleration). Now use the 2nd law again, for the final quantities: Ff= mf af.(The final force equals the final mass times the final acceleration). But the force is constant, so we can set the final and initial forces equal: Ff= mf af = F0= m0 a0. Or
The apple weighs 1N, so F = m g = 1N (this is due to the force of gravity acting on the apple). This means that the apple is exerting a force on your hand of 1N. But the apple originally doesn’t fall, since it is at rest in your hand. This means that by Newton’s 1st law, your hand is exerting an equal and opposite force on the apple of 1N. Therefore the net force on the apple while it is at rest in your hand is zero. After you release the apple, the only force on the apple (neglecting air resistance, etc.) is the force of gravity, so there is a net force on the apple of 1N pointing downward.
4 students (A, B, C, D) pull on ropes that are tied to a 30-kg boulder. If A pulls along the north, B along the south, C along the east and D along the west directions and if D has twice the strength of the other three (120 Newtons against 60), in what direction will the boulder move and with what acceleration?
For this problem, let’s use a 2 dimensional graph, with a y-axis (vertical axis) crossing an x-axis (horizontal