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Course: Middle school physics - NGSS > Unit 1
Lesson 2: Forces and accelerationForces and acceleration
Review your understanding of forces and acceleration in this free article aligned to NGSS standards.
Key points:
- A force is a push or pull on an object.
- A net force is the sum of all of the forces acting on an object.
- When there is a net force on an object, the object will change speed in the direction of the net force. The object’s acceleration tells us how much it speeds up or slows down.
- The acceleration of an object depends on the size of the net force pushing or pulling it and the mass of the object.
- A larger net force creates a larger acceleration.
- A larger mass needs a larger net force to have the same acceleration as a smaller mass.
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How do we remember all this? I´m not kidding.(68 votes)
Practicing more has been shown to aid memory.(44 votes)
Can a force be negative?(27 votes)- Think of a magnet,when you put the two negative ends together do they attract or repel? They repel and that is a negative force.(51 votes)
- The idea of force, mass, and acceleration is the same as the concept of the relation between points x and y. The change of y depends on the change of x and this is commonly known as the rate of change. We can apply the concept of x and y to force and mass for further understanding. For example, If you decide to push an object 100m off a cliff. The amount of force required depends on the mass of the object; if the mass is huge, then the force required to send the object 100m away has to be great. In the example, the force depends on mass, just like y depends on x. So force can be y, mass can be x, and acceleration is the rate of change of force and mass (a=F/m). Force is a function of mass, and acceleration is the rate of change. The concept of force, mass, and acceleration can be graphed as y=mx or f=am.(30 votes)
But what if a massive rocket came and pushed an asteroid , so it was small vs big rocket? What would happen?(17 votes)
it would depend on how much force each rocket is outputting, if the bigger rocket is not efficient it could be giving a lot less force and the smaller rocket would win, and if the bigger rocket is efficient it would most likely work.(15 votes)
can a force be negative(9 votes)
Yes, forces can be negative. Forces have both a magnitude (how "big" of a force) and a direction. A force is negative if it's in the negative direction.
In Physics, we have to define which direction is negative, like putting an imaginary number line in space. We often define down and left as negative. If the force acts in the negative direction, you can say it's a negative force.(9 votes)
How do we remember all this? I´m not kidding.(6 votes)- Copy this article and study it. That's what I am doing.(8 votes)
- Would this help me become an astronomer?(7 votes)
yep it is pretty important(6 votes)
If an object was large and rolled down a hill, would it accelerate faster or just be slow?(6 votes)
It is going down hill so it will go faster depending if the shape of the object was circular or square etc:(2 votes)
How do you measure net force? For example, when a ball rolls down a ramp, you measure the friction and gravitational force as net force (I think). How would that be possible?(7 votes)
Net force is the resulting force of 2 opposing forces. Lets say 2 people, person A and person B, are pushing each other. Person A pushes person B with a force of 50N and person B pushes person A with a force of 20N. The net force is simply 50N - 20N = 30N. You would have to subtract the smaller number from the bigger number to get the resulting (net) force. For your example, the forces involved would be the frictional force and gravitational force. So just subtract the smaller number from the bigger number.
I hope this answers your question.(1 vote)
- Can a force be negative and postitive ?(4 votes)
If a force is negative, it is just indicating the direction. A force can always be positive.(7 votes)
