Table of contents

0. Math Review31m
- Math Review
  31m
1. Intro to Physics Units1h 29m
2. 1D Motion / Kinematics3h 56m
3. Vectors2h 43m
4. 2D Kinematics1h 42m
5. Projectile Motion3h 6m
6. Intro to Forces (Dynamics)3h 22m
7. Friction, Inclines, Systems2h 44m
8. Centripetal Forces & Gravitation7h 26m
9. Work & Energy1h 59m
10. Conservation of Energy2h 54m
11. Momentum & Impulse3h 40m
12. Rotational Kinematics2h 59m
13. Rotational Inertia & Energy7h 4m
14. Torque & Rotational Dynamics2h 5m
15. Rotational Equilibrium3h 39m
16. Angular Momentum3h 6m
17. Periodic Motion2h 9m
18. Waves & Sound3h 40m
19. Fluid Mechanics4h 27m
20. Heat and Temperature3h 7m
21. Kinetic Theory of Ideal Gases1h 50m
22. The First Law of Thermodynamics1h 26m
23. The Second Law of Thermodynamics3h 11m
24. Electric Force & Field; Gauss' Law3h 42m
25. Electric Potential1h 51m
26. Capacitors & Dielectrics2h 2m
27. Resistors & DC Circuits3h 8m
28. Magnetic Fields and Forces2h 23m
29. Sources of Magnetic Field2h 30m
30. Induction and Inductance3h 38m
31. Alternating Current2h 37m
32. Electromagnetic Waves2h 14m
33. Geometric Optics2h 57m
34. Wave Optics1h 15m
35. Special Relativity2h 10m

15. Rotational Equilibrium

Torque & Equilibrium

Physics

15. Rotational Equilibrium

Torque & Equilibrium

Previous problemNext problem

5:07 minutes

Problem 6

Textbook Question

Figure 12–53 shows a pair of forceps used to hold a thin plastic rod firmly. If the thumb and finger each squeeze with a force F_T = F_F = 11.0 N, what force do the forceps jaws exert on the plastic rod?

Verified step by step guidance

Analyze the problem: The forceps act as a type of lever, where the thumb and finger apply forces at one end, and the jaws exert a force on the plastic rod at the other end. The forces applied by the thumb and finger are equal and opposite, creating a torque about the pivot point of the forceps.

Identify the pivot point: The pivot point is the location where the forceps rotate. The forces applied by the thumb and finger create torques about this pivot point, and the force exerted by the jaws on the plastic rod is the result of these torques.

Set up the torque equation: The torque due to the thumb and finger forces must balance the torque exerted by the jaws on the plastic rod. Use the equation for torque: τ = F × d, where F is the force and d is the perpendicular distance from the pivot point to the line of action of the force.

Express the relationship: Let d_T and d_J represent the distances from the pivot point to the thumb/finger forces and the jaws, respectively. The torque balance equation is: F_T × d_T = F_J × d_J, where F_J is the force exerted by the jaws on the plastic rod.

Solve for F_J: Rearrange the equation to find the force exerted by the jaws: F_J = (F_T × d_T) / d_J. Substitute the given values for F_T (11.0 N) and the distances (d_T and d_J) to calculate the force exerted by the jaws.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Newton's Third Law of Motion

Newton's Third Law states that for every action, there is an equal and opposite reaction. This principle is crucial in understanding how forces interact in the system of the forceps and the plastic rod. When the thumb and finger apply forces to the rod, the rod exerts an equal and opposite force back on the forceps, which helps determine the resultant force exerted on the rod.

Force Transmission in Mechanical Systems

In mechanical systems like forceps, forces applied at one point can be transmitted and amplified at another point. The configuration of the forceps allows the forces applied by the thumb and finger to be concentrated at the jaws, resulting in a greater effective force on the plastic rod. Understanding this concept is essential for calculating the total force exerted on the rod.

Equilibrium of Forces

The concept of equilibrium involves the balance of forces acting on an object. In this scenario, the forces exerted by the thumb and finger must be analyzed to determine the net force acting on the plastic rod. If the system is in equilibrium, the total force exerted by the forceps on the rod will equal the sum of the forces applied by the thumb and finger, allowing for a straightforward calculation of the resultant force.

Watch next

Master Torque & Equilibrium with a bite sized video explanation from Patrick

Start learning

Related Videos

Related Practice

Textbook Question

A 2300-kg trailer is attached to a stationary truck at point B, Fig. 12–64. Determine the normal force exerted by the road on the rear tires at A, and the vertical force exerted on the trailer by the support B.

511

views

Textbook Question

Calculate the mass m needed in order to suspend the leg shown in Fig. 12–50. Assume the leg (with cast) has a mass of 15.0 kg, and its cg is 35.0 cm from the hip joint; the cord holding the sling is 78.0 cm from the hip joint.

436

views

Textbook Question

(II) You are on a pirate ship and being forced to walk the plank (Fig. 12–67). You are standing at the point marked C. The plank is nailed onto the deck at point A, and rests on the support 0.75 m away from A. The center of mass of the uniform plank is located at point B. Your mass is 65 kg and the mass of the plank is 45 kg. What is the minimum downward force the nails must exert on the plank to hold it in place?

<IMAGE>

327

views

Textbook Question

The Achilles tendon is attached to the rear of the foot as shown in Fig. 12–76. When a person stands on one foot and lifts the heel to stand on the “ball of one foot,” estimate the tension F_T in the Achilles tendon (pulling upward), and the (downward) force F_B exerted by the lower leg bone on the foot. Assume the person has a mass of 72 kg and D is twice as long as d.

394

views

Textbook Question

A pole projects horizontally from the front wall of a shop. A 6.1-kg sign hangs from the pole at a point 2.2 m from the wall (Fig. 12–88). If the pole is not to fall off, there must be another torque exerted to balance it. What exerts this torque? Use a diagram to show how this torque must act.

373

views

Textbook Question

A pole projects horizontally from the front wall of a shop. A 6.1-kg sign hangs from the pole at a point 2.2 m from the wall (Fig. 12–88). What is the torque due to this sign calculated about the point where the pole meets the wall?

540

views

Textbook Question

If 25 kg is the maximum mass m that a person can hold in a hand when the arm is positioned with a 105° angle at the elbow as shown in Fig. 12–102, what is the maximum force Fₘₐₓ that the biceps muscle exerts on the forearm? Assume the forearm and hand have a total mass of 2.0 kg with a cg that is 15 cm from the elbow, and that the biceps muscle attaches 5.0 cm from the elbow.

533

views

Textbook Question

A woman holds a 1.8-m-long uniform 10.0-kg pole as shown in Fig. 12–84. (a) Determine the forces she must exert with each hand (magnitude and direction). To what position should she move her left hand so that neither hand has to exert a force greater than (b) 150 N? (c) 85 N?

<IMAGE>

476

views

Show more practices