Q: A 2 kg object is dropped from rest near Earth's surface. Ignoring air resistance, what is the distance it falls in 3 seconds? Use $$g = 9.8\ \text{m/s}^2.$$

$$d = (1/2)gt^2$ = (1/2) \times 9.8 \times 3^2$ = 44.1\ \text{m}$$

Q: A spring stretches 0.2 m when a force of 8 N is applied. What is the spring constant $$k$$? (Hooke’s Law: $$F = kx)$$

$$k = F/x = 8/0.2 = 40\ \text{N/m}$$

Q: A 60 kg astronaut travels to a planet where the surface gravity is $$g = 15\ \text{m/s}^2. $$What is her weight on that planet?

$$W = mg = 60 \times 15 = 900\ \text{N}$$

Q: A 3 kg object is accelerated at $$4\ \text{m/s}^2. $$What is the net force acting on it?

$$F = ma = 3 \times 4 = 12\ \text{N}$$

Q: A 10 kg object moves at $$5\ \text{m/s}. $$What is its kinetic energy?

$$KE = (1/2) \times 10 \times 5^2$ = 125\ \text{J}$$

Q: A 4 kg object is pulled 3 m by a force of 20 N. How much work is done?

$$W = Fd = 20 \times 3 = 60\ \text{J}$$

Question 1

Which of the following statements best describes a scientific hypothesis?

Accepted Answer

It is a statement that is testable and can potentially be proven wrong.

Question 2

A car moves at a constant speed around a circular track. Which statement is true about its acceleration?

Accepted Answer

The car has acceleration because its velocity direction changes.

Question 3

A 2 kg object is dropped from rest near Earth's surface. Ignoring air resistance, what is the distance it falls in 3 seconds? Use $$g = 9.8\ 	ext{m/s}^2.$$

Accepted Answer

$$d = (1/2)gt^2$ = (1/2) 	imes 9.8 	imes 3^2$ = 44.1\ 	ext{m}$$

Question 4

Which of the following is a vector quantity?

Accepted Answer

Velocity

Question 5

Two equal forces of 10 N act on an object in opposite directions. What is the net force?

Accepted Answer

0 N

Question 6

A 5 kg box is pushed across a floor at constant velocity. If the friction force is 15 N, what is the applied force?

Accepted Answer

15 N

Question 7

Which formula correctly expresses Newton’s Second Law?

Accepted Answer

$$F = ma$$

Question 8

A spring stretches 0.2 m when a force of 8 N is applied. What is the spring constant $$k$$? (Hooke’s Law: $$F = kx)$$

Accepted Answer

$$k = F/x = 8/0.2 = 40\ 	ext{N/m}$$

Question 9

A 60 kg astronaut travels to a planet where the surface gravity is $$g = 15\ 	ext{m/s}^2. $$What is her weight on that planet?

Accepted Answer

$$W = mg = 60 	imes 15 = 900\ 	ext{N}$$

Question 10

Which of the following statements about mass and weight is correct?

Accepted Answer

Weight changes depending on gravity, but mass stays constant.

Question 11

A 3 kg object is accelerated at $$4\ 	ext{m/s}^2. $$What is the net force acting on it?

Accepted Answer

$$F = ma = 3 	imes 4 = 12\ 	ext{N}$$

Question 12

A 2 kg ball is thrown upward. At the highest point, which statement is true?

Accepted Answer

Velocity is zero, but acceleration is downward.

Question 13

Which formula gives the kinetic energy of a moving object?

Accepted Answer

$$KE = (1/2)mv^2$

Question 14

A 10 kg object moves at $$5\ 	ext{m/s}. $$What is its kinetic energy?

Accepted Answer

$$KE = (1/2) 	imes 10 	imes 5^2$ = 125\ 	ext{J}$$

Question 15

Which of the following energy sources ultimately originates from solar energy?

Accepted Answer

Wind

Question 16

A 4 kg object is pulled 3 m by a force of 20 N. How much work is done?

Accepted Answer

$$W = Fd = 20 	imes 3 = 60\ 	ext{J}$$

Question 17

Which force does no work on an object moving horizontally across a surface?

Accepted Answer

Normal force

Question 18

Which equation describes the gravitational force between two masses?

Accepted Answer

$$F = GMm / r^2$

Question 19

If the radius of a planet doubles but its mass stays the same, what happens to its surface gravity $$g$$? ($$g = GM/R^2$)

Accepted Answer

Surface gravity becomes one-fourth as strong.

PHY101 Exam-1 Study Guide: Physics with Calculus Fundamentals

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