Math Problem Statement

A 3.00 kg block starts from rest at the top of a 26.5 degree incline and slides 2.00 m down the incline in 1.75 s. Find the acceleration of the block, the coefficient of friction between the block and the incline, the frictional force acting on the block, and the speed of the block after it has slid 2.00 m.

Solution

Let’s calculate the quantities step by step.


1. Acceleration of the block

We know:

  • Initial velocity u=0u = 0
  • Distance s=2.00ms = 2.00 \, \mathrm{m}
  • Time t=1.75st = 1.75 \, \mathrm{s}

Using the kinematic equation:

s=ut+12at2s = ut + \frac{1}{2} a t^2

Substituting the known values:

2.00=01.75+12a(1.75)22.00 = 0 \cdot 1.75 + \frac{1}{2} a (1.75)^2

2.00=12a3.06252.00 = \frac{1}{2} a \cdot 3.0625

a=2.0023.0625=1.306m/s2a = \frac{2.00 \cdot 2}{3.0625} = 1.306 \, \mathrm{m/s^2}

The acceleration of the block is:

1.31m/s2\boxed{1.31 \, \mathrm{m/s^2}}


2. Coefficient of friction

On an incline, the net force is given by:

Fnet=ma=mgsinθFfrictionF_{\text{net}} = m a = m g \sin \theta - F_{\text{friction}}

The frictional force is related to the normal force and the coefficient of friction μ\mu:

Ffriction=μFnormal=μmgcosθF_{\text{friction}} = \mu F_{\text{normal}} = \mu m g \cos \theta

Rewriting the net force equation:

ma=mgsinθμmgcosθm a = m g \sin \theta - \mu m g \cos \theta

Dividing through by mgm g:

ag=sinθμcosθ\frac{a}{g} = \sin \theta - \mu \cos \theta

Substituting known values:

  • a=1.31m/s2a = 1.31 \, \mathrm{m/s^2}
  • g=9.8m/s2g = 9.8 \, \mathrm{m/s^2}
  • θ=26.5\theta = 26.5^\circ

1.319.8=sin(26.5)μcos(26.5)\frac{1.31}{9.8} = \sin(26.5^\circ) - \mu \cos(26.5^\circ)

0.1337=0.4462μ(0.8949)0.1337 = 0.4462 - \mu (0.8949)

μ(0.8949)=0.44620.1337\mu (0.8949) = 0.4462 - 0.1337

μ=0.31250.8949=0.349\mu = \frac{0.3125}{0.8949} = 0.349

The coefficient of friction is:

0.349\boxed{0.349}


3. Frictional force acting on the block

The frictional force is given by:

Ffriction=μmgcosθF_{\text{friction}} = \mu m g \cos \theta

Substituting known values:

  • μ=0.349\mu = 0.349
  • m=3.00kgm = 3.00 \, \mathrm{kg}
  • g=9.8m/s2g = 9.8 \, \mathrm{m/s^2}
  • cos(26.5)=0.8949\cos(26.5^\circ) = 0.8949

Ffriction=0.3493.009.80.8949F_{\text{friction}} = 0.349 \cdot 3.00 \cdot 9.8 \cdot 0.8949

Ffriction=9.18NF_{\text{friction}} = 9.18 \, \mathrm{N}

The frictional force acting on the block is:

9.18N\boxed{9.18 \, \mathrm{N}}


4. Speed of the block after sliding 2.00 m

Using the kinematic equation:

v2=u2+2asv^2 = u^2 + 2 a s

Substituting known values:

  • u=0m/su = 0 \, \mathrm{m/s}
  • a=1.31m/s2a = 1.31 \, \mathrm{m/s^2}
  • s=2.00ms = 2.00 \, \mathrm{m}

v2=0+2(1.31)(2.00)v^2 = 0 + 2 (1.31)(2.00)

v2=5.24v^2 = 5.24

v=5.24=2.29m/sv = \sqrt{5.24} = 2.29 \, \mathrm{m/s}

The speed of the block after sliding 2.00 m is:

2.29m/s\boxed{2.29 \, \mathrm{m/s}}


Final Answers:

  1. Acceleration: 1.31m/s2\boxed{1.31 \, \mathrm{m/s^2}}
  2. Coefficient of friction: 0.349\boxed{0.349}
  3. Frictional force: 9.18N\boxed{9.18 \, \mathrm{N}}
  4. Speed after sliding 2.00 m: 2.29m/s\boxed{2.29 \, \mathrm{m/s}}

Would you like further clarifications or details?

Related Questions:

  1. How does the angle of incline affect the coefficient of friction?
  2. What happens to the frictional force if the block's mass changes?
  3. How is the acceleration influenced by increasing the coefficient of friction?
  4. Can the coefficient of friction exceed 1? Why or why not?
  5. How would the speed change if the incline were frictionless?

Tip:

When working with inclined planes, always resolve forces parallel and perpendicular to the incline for a clear

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Math Problem Analysis

Mathematical Concepts

Kinematics
Newton's Laws of Motion
Forces on an Incline
Friction

Formulas

s = ut + 0.5at^2
F_net = ma = mg*sin(θ) - μmg*cos(θ)
μ = (sin(θ) - a/g) / cos(θ)
F_friction = μmg*cos(θ)
v^2 = u^2 + 2as

Theorems

Newton's Second Law
Kinematic Equations of Motion

Suitable Grade Level

Grades 9-12