# Three girls pull a sled. Determine the acceleration.

• Natko
In summary: So the acceleration is the acceleration that occurs at the instant the force is applied.In summary, the problem involves two girls pulling a sled across a snowy field while a third girl pulls backwards with a 2.0 N force. Using the formula F=ma, the net force on the sled can be determined by adding all the forces together. By finding the horizontal and vertical components of the forces, the net force can be calculated to be 14.39 N at an angle of 5.67 degrees down of left. The instantaneous acceleration of the sled can then be found by dividing the net force by the mass, resulting in an acceleration of 1.439 m/s^2.
Natko

## Homework Statement

Two girls pull a sled across a field of snow, as shown in the diagram. A third girl pulls backward with a 2.0 N force. If the mass of the sled is 10 kg, determine its instantaneous acceleration.

F=ma

## The Attempt at a Solution

Sorry, I'm stumped.

You want to find the net force on the block. Do you have any ideas about how to work this out?

To give some further input:

1) forces (pulling) are vectorial, which means they can be added by "putting them tip on tail". So, the net force is the sum over all forces.
2) Can you somehow determine the horizontal and vertical component of the forces?

BOYLANATOR said:
You want to find the net force on the block. Do you have any ideas about how to work this out?

MortalWombat said:
To give some further input:

1) forces (pulling) are vectorial, which means they can be added by "putting them tip on tail". So, the net force is the sum over all forces.
2) Can you somehow determine the horizontal and vertical component of the forces?

Thanks for the tips. I'll try:

Fy=10sin30-10sin40
=-1.428 N
Fx= 10cos30+10cos40-2
=14.32 N
√(Fy2+Fx2)=14.39 N
Θ=tan-1(Fy/Fx)
=5.67
a=F/m
=1.439 m/s2 [5.67 down of left]

Is that correct, or did I mess up somewhere? What does the question mean by "instantaneous?" I know what the word means, but how does it affect this question?

Last edited:
Natko said:
Thanks for the tips. I'll try:

Fy=10sin30-10sin40
=-4.28 N

Numerical error in here. The rest of the working looks good

1 person
Instantaneous means happening at this instant. It is unlikely that the girls could all pull with constant force in a constant direction for an extended time.

## 1. What is the formula for acceleration?

The formula for acceleration is a = (vf - vi)/t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time.

## 2. How do you determine the acceleration of an object?

To determine the acceleration of an object, you need to measure its change in velocity over a specific amount of time. This can be done by using the formula a = (vf - vi)/t or by graphing the object's motion and finding the slope of the line.

## 3. What is the unit of measurement for acceleration?

The unit of measurement for acceleration is meters per second squared (m/s^2).

## 4. How does the mass of the sled affect its acceleration?

The mass of the sled does not directly affect its acceleration. According to Newton's second law of motion, the acceleration of an object depends on the net force acting on it and its mass. So, if the force applied by the girls is the same, the acceleration will be the same regardless of the sled's mass.

## 5. Can you determine the acceleration of the sled if the force applied by the girls is not known?

No, the acceleration of the sled cannot be determined without knowing the force applied by the girls. According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it.

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