On which factors force of friction depends?
The roughness of the contact surface and the weight of the object that moves.
What happens to the moticn of an object when the forces on it are balanced?
If it is static, it will stay static. If it is in motion, it will continue to move in the same direction and at the same speed. (Newton's first law).
A sailing boat has a forwards force of 300 N from lhe wind in its saiIs. It is travelling at a constant speed. What is the total force acting on Ihe sailing boat? Explain your answer.
It is travelling with constant speed, which means that a net (resultant) force does not act on an object (Newton first law). Therefore Ft=0 N.
The same force is used to accelerate a small car and a monster car. Whal will be different about their motions? Explain your answer.
The acceleration of the monster car will be smaller due to its greater mass (Newton's second law)
Explain why two objects dropped on the Moon will accelerate at the same rate, even when they have different masses.
The gravitational force on the heavier object will be larger, but a larger force is needed to accelerate heavier objects, so one thing compensates the other.
Explain why Formula 1 racing cars have low masses.
Because, the lower the mass the higher the acceleration (Newton's second law).
Explain why oil tankers (which have masses of about half a million tons) take about 20 minutes to stop moving when their engines are turned off.
A more massive object has a greater tendency to resist changes in its state of motion. The higher the mass, the lower the acceleration (Newton's second law).
Explain why a passenger, who is standing, might lose his balance if a train accelerates quickly out of a station.
Because the passenger is static, and he tends to remain static as no force acts on him (Newton´s first law).
Explain why when you are swimming you have to push water backwards so that you can move forwards.
When you push the water backwards, the water exerts on you a reaction force that is equal in magnitude and opposite in direction (Newton's third law).
Explain why you cannot walk easily on icy ground.
When we walk, we push the road backwards. Due to friction, the road pushes us forwards with an equal and opposite force (Newton's third law).
Explain why passengers should wear seat belts in cars and coaches.
Because if you are not strapped in, you keep moving until you hit something in front (Newton's first law).
Explain why a gun recoils backwards when fired.
The gun exerts a force on the bullet in the forward direction. The bullet also exerts an equal and opposite force on the gun (Newton's third law).
Determine the reaction force involved when a ball is hit with a racquet with a force of 100 N west.
The force of the ball pushing back against the strings of the racquet (Newton's third law).
Does rubber in the extension-Ioad graph obey Hooke's law? Explain.
No, because Hooke's law says that the deformation of an elastic material is proportional to the force applied to it and thus we would get a linear graph.
You are helping a friend move furniture. The friend asks you to stand inside the back of a pickup truck to hold a piano because there is no rope available to tie it to the truck. Explain why you should refuse this request.
For starters, you wouldn't be strapped yourself. Besides, if there was a crash you are not nearly strong enough to stop the piano, as it has a large mass.
when a horse pulls on a cart, the cart pulls back with an equal force on the horse. If, in fact, the cart pulls back on the horse as hard as the horse pulls forward on the cart, how is it possible for the horse to move the cart?
Because this is not the force from which motion comes from. Motion comes from the horse pushing the road and the road pushing the horse forward.
