Question 1

Eratosthenes measured the circumference of the Earth by comparing the angle of the Sun's rays at two different locations. If the distance between the two cities was 800 km and the angle difference was $$7.2^	ext{o}$$, what is the approximate circumference of the Earth?

Accepted Answer

$$40000\ 	ext{km}$$

Question 2

Which of the following best describes a scientific hypothesis?

Accepted Answer

A tentative explanation that can be tested by experiments or observations.

Question 3

Which of the following is NOT a step in the scientific method?

Accepted Answer

Ignoring contradictory evidence

Question 4

Galileo's Leaning Tower of Pisa experiment demonstrated that:

Accepted Answer

Objects of different masses fall at the same rate in the absence of air resistance.

Question 5

A car accelerates from rest to $$20\ 	ext{m/s} in$$ $$10\ 	ext{s}. $$What is its acceleration?

Accepted Answer

$$2\ 	ext{m/s}^2$$

Question 6

Which of the following statements about mechanical equilibrium is correct?

Accepted Answer

The sum of all forces acting on the object is zero.

Question 7

If the net force acting on an object is zero, which of the following is true?

Accepted Answer

The object is either at rest or moving at constant velocity.

Question 8

Which formula correctly expresses Newton's Second Law of Motion?

Accepted Answer

$$F = ma$$

Question 9

A box of mass $$5\ 	ext{kg} is $$pushed with a force of $$20\ 	ext{N}. $$What is its acceleration?

Accepted Answer

$$4\ 	ext{m/s}^2$$

Question 10

Which of the following is the correct equation for gravitational force between two masses $$m_1$$ and $$m_2$$ separated by distance $$r$$?

Accepted Answer

$$F = G \frac{m_1$ m_2$}{r^2$}$$

Question 11

If the distance between two objects is doubled, what happens to the gravitational force between them?

Accepted Answer

It becomes one-fourth as strong.

Question 12

Which of the following best describes kinetic energy?

Accepted Answer

The energy an object has due to its motion.

Question 13

What is the equation for kinetic energy?

Accepted Answer

$$KE = \frac{1}{2}mv^2$

Question 14

A $$2\ 	ext{kg}$$ object is lifted to a height of $$5\ 	ext{m}. $$What is its potential energy? (Assume $$g = 10\ 	ext{m/s}^2)$$

Accepted Answer

$$100\ 	ext{J}$$

Question 15

Which of the following is a correct statement of the law of conservation of energy?

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 16

A machine has an efficiency of $$40\%. If $$you input $$500\ 	ext{J} of $$energy, how much useful work does the machine output?

Accepted Answer

$$200\ 	ext{J}$$

Question 17

Which of the following best explains why the moon does not fall to Earth?

Accepted Answer

It is moving fast enough tangentially to stay in orbit due to Earth's gravity.

Question 18

If a $$10\ 	ext{kg}$$ object is dropped from rest, what is its acceleration due to gravity (neglecting air resistance)?

Accepted Answer

$$9.8\ 	ext{m/s}^2$$

Question 19

Which of the following is a vector quantity?

Accepted Answer

Velocity

Question 20

A person jumps up in the air. While in the air, why do they stay with the motion of the Earth?

Accepted Answer

Because they retain the Earth's rotational velocity due to inertia.

Physics Midterm Study Guide: Fundamental Concepts and Laws

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