# Dynamics problems(force and friction and such)

• thelegend123
In summary: Your Fnet is equal to your friction force, right? What is your formula for finding the force of friction?The force of friction is the force that resists the motion of two objects. It is calculated by the equation Fnet = Fn*(1-Coefficient of friction).
thelegend123
3 problems

1. A 2.0 kg object is traveling at a constant speed of 1.4m/s[N] when it hits and ice patch. over the first 0.40m of the ice patch the object slows down to 0.85m/s[N]. what is coefficient of friction of the ice? (starting on a frictionless surface then slowing down)

2. an object starts from rest and then travels 6.0m
in 4.0s. if the coefficient of friction is 0.10 and there was an applied force of 9.0N
, what was the mass of the object?

3. Mr.Yahoo is pulling her friend's kids in a wagon with a force of 150N [E30*up] (which is equivalent to 130 N [E] and 75 N [up}. if the kids weigh 12kg, 8.0kg and the wagon weighs 3.0kg and the coefficient of friction is 0.43, what is their acceleration?

Thank you in advance, please try to show full work and calculations and an idea of what a freebody diagram looks like.​

welcome to pf!

hi thelegend123! welcome to pf

show us what you've tried, and where you're stuck, and then we'll know how to help!

tiny-tim said:
hi thelegend123! welcome to pf

show us what you've tried, and where you're stuck, and then we'll know how to help!

i stated all of my variables

i found the Fg = 19.6N and Fn = 19.6N i don't know where to go from here

do the geometry first, then the physics

the geometry is to find the acceleration from the data

then use physics to find the force, and then the coefficient of friction

what do you get?

tiny-tim said:
do the geometry first, then the physics

the geometry is to find the acceleration from the data

then use physics to find the force, and then the coefficient of friction

what do you get?

not tosure on how to find accel?

would it be using a kinematic equation v2^2 = v1^2 + 2ad

but i don't think D has direction

thelegend123 said:
would it be using a kinematic equation v2^2 = v1^2 + 2ad

that's right
but i don't think D has direction

i don't understand

(anyway, now I'm off to bed :zzz:)

tiny-tim said:
do the geometry first, then the physics

the geometry is to find the acceleration from the data

then use physics to find the force, and then the coefficient of friction

what do you get?

i got acceleration is -1.5ish and Fnet is 3.1N

what now?

Good. Your Fnet is equal to your friction force, right? What is your formula for finding the force of friction?

## 1. What is the difference between static and kinetic friction?

Static friction is the force that resists the motion of an object at rest, while kinetic friction is the force that opposes the motion of an object in motion.

## 2. How do you calculate the net force on an object?

The net force on an object can be calculated by adding together all the individual forces acting on the object. This can be done using vector addition or by using Newton's Second Law, F=ma, where F is the net force, m is the mass of the object, and a is the acceleration.

## 3. What is the relationship between force and acceleration?

According to Newton's Second Law, force and acceleration are directly proportional. This means that as the force acting on an object increases, the acceleration of the object also increases, and vice versa.

## 4. How does friction affect an object's motion?

Friction acts as a resistive force that opposes the motion of an object. It can either slow down or prevent the object from moving altogether. The amount of friction depends on the type of surfaces in contact and the force pushing the surfaces together.

## 5. Can an object have a net force of 0 and still be moving?

Yes, an object can have a net force of 0 and still be moving if the individual forces acting on the object cancel each other out. This can occur when there is an equal and opposite force acting on the object, or when the object is moving at a constant velocity.

Replies
12
Views
2K
Replies
3
Views
4K
Replies
9
Views
4K
Replies
12
Views
7K
Replies
4
Views
2K
Replies
15
Views
3K
Replies
7
Views
4K
Replies
5
Views
9K
Replies
2
Views
3K
Replies
14
Views
10K