Q: A force of $$10 \ \text{N} is $$applied perpendicular to a wrench at a distance of $$0.3 \ \text{m}$$ from the bolt. What is the torque produced?

$$3 \ \text{N} \cdot \text{m}$$

Q: A $$2 \ \text{kg}$$ block is placed $$1 \ \text{m}$$ from a pivot, and a $$1 \ \text{kg}$$ block is placed $$2 \ \text{m}$$ from the pivot on the opposite side. What is the net moment about the pivot?

$$0 \ \text{N} \cdot \text{m}$$

Q: A force of $$8 \ \text{N} is $$applied at an angle of $$30^\circ to a $$lever arm of $$0.5 \ \text{m}. $$What is the magnitude of the torque produced?

$$2 \ \text{N} \cdot \text{m}$$

Q: Which of the following is the correct formula for stress?

$$\text{stress} = \frac{\text{force}}{\text{cross-sectional area}}$$

Q: A steel cable with a cross-sectional area of $$2 \times 10$$^{-4}$$ \ \text{m}^2$$ supports a load of $$4000 \ \text{N}. $$What is the stress in the cable?

$$2 \times 10$$^{7}$$ \ \text{N/m}^2$$

Question 1

A uniform beam is balanced on a pivot at its center. A 3 kg mass is hung 2 m to the left of the pivot. At what distance to the right of the pivot should a 2 kg mass be hung to balance the beam?

Accepted Answer

$$3 \ 	ext{m}$$

Question 2

Which of the following best describes the center of gravity of an object?

Accepted Answer

The point where the resultant torque due to gravity is zero.

Question 3

A force of $$10 \ 	ext{N} is $$applied perpendicular to a wrench at a distance of $$0.3 \ 	ext{m}$$ from the bolt. What is the torque produced?

Accepted Answer

$$3 \ 	ext{N} \cdot 	ext{m}$$

Question 4

Which of the following is NOT a condition for equilibrium?

Accepted Answer

The object must be at rest.

Question 5

A gymnast balances horizontally on a beam. If her center of gravity is not directly above the beam, what will happen?

Accepted Answer

She will rotate until her center of gravity is above the beam.

Question 6

A $$2 \ 	ext{kg}$$ block is placed $$1 \ 	ext{m}$$ from a pivot, and a $$1 \ 	ext{kg}$$ block is placed $$2 \ 	ext{m}$$ from the pivot on the opposite side. What is the net moment about the pivot?

Accepted Answer

$$0 \ 	ext{N} \cdot 	ext{m}$$

Question 7

Which of the following statements about torque is correct?

Accepted Answer

A torque that tends to rotate an object in a counterclockwise direction is positive.

Question 8

A force of $$8 \ 	ext{N} is $$applied at an angle of $$30^\circ to a $$lever arm of $$0.5 \ 	ext{m}. $$What is the magnitude of the torque produced?

Accepted Answer

$$2 \ 	ext{N} \cdot 	ext{m}$$

Question 9

Which of the following best describes a couple in physics?

Accepted Answer

A pair of equal and opposite forces whose lines of action do not coincide.

Question 10

According to Hooke's Law, what is the restoring force $$F in a $$spring with spring constant $$k$$ and extension $$x$$?

Accepted Answer

$$F = kx$$

Question 11

A wire of original length $$2 \ 	ext{m}$$ stretches by $$0.01 \ 	ext{m}$$ under a load. What is the strain in the wire?

Accepted Answer

$$0.005$$

Question 12

Which of the following is the correct formula for stress?

Accepted Answer

$$	ext{stress} = \frac{	ext{force}}{	ext{cross-sectional area}}$$

Question 13

A steel cable with a cross-sectional area of $$2 	imes 10$$^{-4}$$ \ 	ext{m}^2$$ supports a load of $$4000 \ 	ext{N}. $$What is the stress in the cable?

Accepted Answer

$$2 	imes 10$$^{7}$$ \ 	ext{N/m}^2$$

Question 14

Which of the following best describes Young's modulus?

Accepted Answer

It is the ratio of stress to strain.

Question 15

A $$1 \ 	ext{m}$$ long tendon stretches by $$1 \ 	ext{mm}$$ under a force of $$1.2 \ 	ext{N}. If $$its cross-sectional area is $$5 	imes 10$$^{-6}$$ \ 	ext{m}^2$$, what is the Young's modulus of the tendon?

Accepted Answer

$$2.4 	imes 10$$^{8}$$ \ 	ext{N/m}^2$$

Question 16

Which of the following is NOT a type of stress?

Accepted Answer

Thermal stress

Question 17

A material is said to be in static equilibrium if:

Accepted Answer

The sum of all forces and the sum of all torques acting on it are zero.

Question 18

Which of the following best describes stable equilibrium?

Accepted Answer

When displaced, the object returns to its original position.

Question 19

A force of $$4 \ 	ext{N} is $$applied at an effective lever arm of $$22 \ 	ext{cm} at an $$angle of $$30^\circ. $$What is the torque produced?

Accepted Answer

$$0.44 \ 	ext{N} \cdot 	ext{m}$$

Equilibrium and Elasticity: Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드