Free help with homework

Why join Brainly?

  • ask questions about your assignment
  • get answers with explanations
  • find similar questions

A block of mass 2kg rests on a rough inclined plane making an angle of 30degree with the horizontal.the coefficient of ststic friction between the block

and the plane is 0.7.What is the magnitude of the friction force on the block?(g=908meter/second square)


Given, m = 2 kg
θ = 30 degree
μ = 0.7

As it is clear for figure :
R = m g cos ​θ
Therefore, force of friction, F = ​μ R = ​μ m g cos ​θ = 0.7 X 2 X 9.8 X cos 30 = 11.86 N
0 0 0

This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
See the diagram.
If the block is resting with out slipping on the inclined surface, it means that the frictional force is greater than the gravitational pull down the plane. we calculate the minimum value of static friction at the surface of the block.

Friction force Ff = coeff of static friction * Normal force
         Ff           = Mu * N
Normal force N = mg cos Ф  as the block is in equilibrium. and net force in the  direction of perpendicular to plane is zero.  Ф is the angle of inclination of plane.

        Ff = Mu * m g Cos Ф = 0.7 * 2 kg * 9.8m/s² * cos 30 = 11.88 Newtons

Suppose we calculate the component of weight along the inclined plane:
       = m g Sin Ф = 2 kg * 9.8m/s² * sin 30 = 9.8 Newtons

So we see that the static frictional force is higher than the gravity along the inclined plane, so the block rests.

If Ф is increased, cos Ф reduces and sin Ф increases, and then there will be a point when the block starts to slide.

0 0 0
The Brain
  • The Brain
  • Helper
Not sure about the answer?
Learn more with Brainly!
Having trouble with your homework?
Get free help!
  • 80% of questions are answered in under 10 minutes
  • Answers come with explanations, so that you can learn
  • Answer quality is ensured by our experts