# Magnitude of acceleration of a stationary mass

• peaceandlove
In summary, the block of mass accelerating across the floor due to the force applied at angle 20 degrees with the horizontal is 0.510mg.
peaceandlove

## Homework Statement

An initially stationary block of mass m lies on the floor. A force of magnitude 0.500mg is then applied at upward angle θ = 20°. What is the magnitude of the acceleration of the block across the floor if (a) μs = 0.620 and μk = 0.520 and (b) μs = 0.410 and μk = 0.310?

Fx=.5mgcos20
Fy=.5mgsin20

## The Attempt at a Solution

I first found my force in the x and y directions by using: Fx=Fcos(theta) = 0.5mgcos(theta)
Fy=Fsin(theta) = 0.5mgsin(theta). Since I had to find the normal force (in order to find out the static friction) i used: Fnet,y=may => Fn-Fg-Fy=may and since its not accelerating in the y direction ay=0 making: Fn=Fg+Fy => mg+0.5mgsin(theta), then i found the max static friction by using: Mu*normal force when i compared my max static friction to my Force in the x direction (since that's the only direction its moving), my static friction was less than my Fx, making a=0. And then i did that again for the second set of numbers for part b, got the same thing, a=0, but got it wrong. So i don't know what to do from there.

Last edited:
mg acts in the downward direction. Take its component perpendicular and parallel to the inclined plane. Perpendicular component will be the normal reaction. From this find the frictional force which is along the inclined plane. Now porceed.

Sorry. Ignore the post #2.
Since force is acted in the upward direction with angle 20 degree with horizontal, mg and Fy must be in the opposite direction. So Fn must be mg - Fy

Last edited:
peaceandlove: Although your approach is currently incorrect, you got the answer for part (a) correct, right? Only your answer for part (b) was wrong, true?

Fn is not equal to m*g + 0.5*m*g*sin(theta). Try again. You also said, "My static friction was less than my Fx, making a = 0." Are you sure this statement is correct?

## What is the magnitude of acceleration of a stationary mass?

The magnitude of acceleration of a stationary mass is zero, as the object is not moving and therefore not experiencing any change in velocity.

## Does the magnitude of acceleration of a stationary mass vary?

No, the magnitude of acceleration of a stationary mass does not vary as long as the mass remains stationary. It will only change if an external force is applied to the mass.

## What factors affect the magnitude of acceleration of a stationary mass?

The magnitude of acceleration of a stationary mass is affected by the mass of the object, the force applied to it, and the surface it is resting on.

## How is the magnitude of acceleration of a stationary mass measured?

The magnitude of acceleration of a stationary mass can be measured using a device called an accelerometer, which detects changes in acceleration and can accurately measure its magnitude.

## Why is the magnitude of acceleration of a stationary mass important?

The magnitude of acceleration of a stationary mass is important in understanding the dynamics of objects at rest and how external forces can affect their state. It is also a key component in Newton's Second Law of Motion, which states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass.

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