# Physics Help

posted by .

A force sensor is used to measure a force applied to a 9.1 kg box on a hard, horizontal surface. It records that the box starts to move when the force is equal to 26.9 N. This force makes the box start to move with an acceleration of 0.2 m/s2. Find mu sub s/k respectively.

• Physics Help -

F(fr) =μ•N = μ•m•g

1. F(fr)=F
μ(s)•m•g =F,
μ(s) =F/m•g =26.9/9.1•9.8 = 0.3

2. m•a=F(fr)
m•a = μ(k)•m•g
μ(k)=a/g=0.2/9.8=0.2

• Physics Help -

First compute mu(static):
When the box just begins to move, the applied force equals mu(s)*m*g
So mu(s)= F/m*g = 26.9/(9.1*9.8)= 0.30

Now when the box gets into motion, mu(k) comes in picture and frictional force f = mu(k)*m*g
So F - mu(k)*m*g = m*a
mu(k) = (F - m*a)/m*g
= (26.9-9.1*0.2)/9.1*9.8
= 0.28

## Similar Questions

1. ### physics

A box of Cheerios and a box of Wheaties are accelerated accross a horizontal force vector F applied to the Cheerios box. THe magnitude of the frictional force on the Cheerios box is 2 N and the magnitude of the frictional force on …
2. ### Physics

You pushed a 1 kg box on floor where= 0.3. If the force you applied was 5 N, will the box move?
3. ### Physics

A force sensor is used to measure a force applied to a 7.5 kg box on a hard, horizontal surface. It records that the box starts to move when the force is equal to 16.5 N. This force makes the box start to move with an acceleration …
4. ### Physics

A 10-kg wooden box rests on a ramp that is lying flat. The coefficient of static friction is 0.50, and the coefficient of kinetic friction is 0.30. What is the friction force between the box and ramp if no force horizontal force is …
5. ### Physics

Two boxes on a horizontal surface, as shown in the figure above, are moving together under the influence of a horizontal force, F. The coefficient of kinetic friction between the boxes and the surface is 0.40. Use g = 10 m/s2. In case …
6. ### physics

Two boxes (b1 = 23 kg and b2 = 57 kg) are being pushed across a horizontal frictionless surface, as the drawing shows. The 48-N pushing force is horizontal and is applied to the 23-kg box, which in turn pushes against the 57-kg box. …
7. ### Physics

ohh sorry, in my first question... A 15 kg box sits on a horizontal FORCE. the coefficient of static fricition between the box and the surface is 0.70. if a force P is exerted on the box at an angle directed 37 degrees below the horizontal, …
8. ### Physics-forces

1. a force of 250N is used to push a heavy box down the street. If the force of friction between the box and the street is 195N and the box has a mass of 60kg, what is the accleration of the box?
9. ### physics

A)Two boxes sit side-by-side on a smooth horizontal surface. The lighter box has a mass of 5.60 kg, the heavier box has a mass of 7.65 kg. Calculate the contact force between these boxes when a horizontal force of 4.83 N is applied …
10. ### physics

A box is being accelerated across a rough, level surface. A force is being applied to the box in an upward and a rightward direction (as shown below). This force makes an angle of 30 degrees with the horizontal. The force of friction …

More Similar Questions