Math Problem Statement

An applied force of 60 N accelerates an 8.5 kg object. The object is slowed by a frictional force of 11 N.

What are the normal force, acceleration, and net force acting on the object?

Solution

To analyze this problem, we’ll break down the forces involved and use Newton's laws to find the normal force, acceleration, and net force.

Given Information

  • Applied force, Fapplied=60NF_{\text{applied}} = 60 \, \text{N}
  • Mass of the object, m=8.5kgm = 8.5 \, \text{kg}
  • Frictional force, Ffriction=11NF_{\text{friction}} = 11 \, \text{N}
  • Gravitational acceleration, g9.8m/s2g \approx 9.8 \, \text{m/s}^2

1. Normal Force

The normal force FnormalF_{\text{normal}} is the force exerted by a surface perpendicular to the object, typically balancing the gravitational force if there are no vertical accelerations. Assuming the object is on a flat surface and there’s no vertical movement:

Fnormal=mgF_{\text{normal}} = m \cdot g

Substitute in the values:

Fnormal=8.5kg×9.8m/s2=83.3NF_{\text{normal}} = 8.5 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 83.3 \, \text{N}

So, the normal force is 83.3N83.3 \, \text{N}.

2. Net Force

To find the net force, FnetF_{\text{net}}, we consider both the applied force and the frictional force. The frictional force opposes the applied force, so it will be subtracted:

Fnet=FappliedFfrictionF_{\text{net}} = F_{\text{applied}} - F_{\text{friction}}

Substitute the values:

Fnet=60N11N=49NF_{\text{net}} = 60 \, \text{N} - 11 \, \text{N} = 49 \, \text{N}

So, the net force is 49N49 \, \text{N}.

3. Acceleration

Using Newton's second law, F=maF = m \cdot a, we can solve for the acceleration aa by rearranging it to:

a=Fnetma = \frac{F_{\text{net}}}{m}

Substitute the known values:

a=49N8.5kg5.76m/s2a = \frac{49 \, \text{N}}{8.5 \, \text{kg}} \approx 5.76 \, \text{m/s}^2

Thus, the acceleration of the object is approximately 5.76m/s25.76 \, \text{m/s}^2.


Summary of Results

  • Normal Force: 83.3N83.3 \, \text{N}
  • Net Force: 49N49 \, \text{N}
  • Acceleration: 5.76m/s25.76 \, \text{m/s}^2

Would you like further details on any part?


Related Questions to Explore

  1. How does increasing the frictional force affect the net force and acceleration?
  2. What would the net force be if the applied force were reduced by half?
  3. If the object were on an incline, how would the normal force calculation change?
  4. How would doubling the mass affect the acceleration?
  5. What would happen to the acceleration if the frictional force increased to match the applied force?

Tip:

Remember, friction always acts in the opposite direction to the applied force, reducing the net force and thus affecting acceleration directly.

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Math Problem Analysis

Mathematical Concepts

Newton's Second Law
Forces
Kinematics

Formulas

Normal force: F_normal = m * g
Net force: F_net = F_applied - F_friction
Acceleration: a = F_net / m

Theorems

Newton's Second Law of Motion

Suitable Grade Level

Grades 9-11