Q: A 1 kg object is dropped from rest from a height of 20 m. Neglecting air resistance, what is its speed just before hitting the ground? (Use $$g = 9.8\,\mathrm{m/s^2$})$$

$$v = \sqrt{2gh} = \sqrt{2 \times 9.8 \times 20} \approx 19.8\,\mathrm{m/s}$$

Question 1

Which of the following statements best describes the difference between distance and displacement?

Accepted Answer

Distance is the total path length traveled, while displacement is the straight-line change in position from the initial to the final point.

Question 2

A car travels 100 m east, then 75 m west. What is the car’s displacement?

Accepted Answer

$$\Delta x = 100\,\mathrm{m} - 75\,\mathrm{m} = 25\,\mathrm{m}$$ east

Question 3

Which of the following is the correct SI unit for acceleration?

Accepted Answer

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

Question 4

A runner completes one lap around a 400 m track in 50 s. What is the runner’s average velocity?

Accepted Answer

$$v_{av} = 0\,\mathrm{m/s}$$

Question 5

A ball is thrown straight up with an initial velocity of $$10\,\mathrm{m/s}. $$What is its velocity at the highest point?

Accepted Answer

$$0\,\mathrm{m/s}$$

Question 6

Which of the following equations correctly gives the position $$x as a $$function of time $$t$$ for an object with constant acceleration $$a$$ and initial velocity $$v_0$$?

Accepted Answer

$$x = x_0$ + v_0$ t + \dfrac{1}{2} a t^2$

Question 7

A projectile is launched horizontally from a cliff of height $$h$$ with speed $$v_0. $$Neglecting air resistance, what is the time it takes to hit the ground?

Accepted Answer

$$t = \sqrt{\dfrac{2h}{g}}$$

Question 8

A vector has components $$A_x = 3$$ and $$A_y = 4. $$What is the magnitude of the vector?

Accepted Answer

$$|\vec{A}| = 5$$

Question 9

A car accelerates from rest at $$2\,\mathrm{m/s^2$}$$ for $$5\,\mathrm{s}. $$What is its final velocity?

Accepted Answer

$$v = 10\,\mathrm{m/s}$$

Question 10

A 2 kg object is acted on by a net force of $$10\,\mathrm{N}. $$What is its acceleration?

Accepted Answer

$$a = 5\,\mathrm{m/s^2$}$$

Question 11

A block slides across a horizontal surface with a coefficient of kinetic friction $$\mu_k = 0.2. If $$the block’s mass is $$5\,\mathrm{kg}$$, what is the magnitude of the frictional force?

Accepted Answer

$$f_k = 10\,\mathrm{N}$$

Question 12

A 70 kg astronaut pushes on a 140 kg satellite in space. If the astronaut exerts a force of $$F on $$the satellite, what force does the satellite exert on the astronaut?

Accepted Answer

$$F$$, in the opposite direction

Question 13

A ball is thrown at an angle $$	heta$$ above the horizontal with initial speed $$v_0. $$Which of the following is true about the horizontal component of its velocity (neglecting air resistance)?

Accepted Answer

It remains constant throughout the flight.

Question 14

A 10 kg box is at rest on a horizontal table. What is the normal force exerted by the table on the box?

Accepted Answer

$$F_N = 98\,\mathrm{N}$$

Question 15

A block is pulled up a frictionless incline at constant speed. Which statement is true about the net force acting on the block?

Accepted Answer

The net force is zero.

Question 16

A 5 kg object is suspended by a massless rope. What is the tension in the rope?

Accepted Answer

$$T = 49\,\mathrm{N}$$

Question 17

A spring with force constant $$k = 200\,\mathrm{N/m} is $$stretched $$0.1\,\mathrm{m}$$ from equilibrium. What is the force exerted by the spring?

Accepted Answer

$$F = 20\,\mathrm{N}$$

Question 18

A 1 kg object is dropped from rest from a height of 20 m. Neglecting air resistance, what is its speed just before hitting the ground? (Use $$g = 9.8\,\mathrm{m/s^2$})$$

Accepted Answer

$$v = \sqrt{2gh} = \sqrt{2 	imes 9.8 	imes 20} \approx 19.8\,\mathrm{m/s}$$

Physics with Calculus: Foundations, Kinematics, and Vectors

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