Q: Which of the following best describes free fall near Earth's surface?

Objects accelerate downward at $$9.8\ \text{m/s}^2$$ regardless of their initial velocity.

Question 1

A car accelerates from rest at a constant rate of $$2.0\ 	ext{m/s}^2$$ for $$5.0\ 	ext{s}. $$What is its final velocity?

Accepted Answer

$$10\ 	ext{m/s}$$

Question 2

Which of the following statements about acceleration is TRUE?

Accepted Answer

Acceleration is the rate of change of velocity and is a vector quantity.

Question 3

A velocity-time graph for an object shows a straight line with a positive slope. What does this indicate about the object's motion?

Accepted Answer

The object is accelerating at a constant rate.

Question 4

A Boeing 747 accelerates at $$2.6\ 	ext{m/s}^2$$ from rest to a takeoff speed of $$70\ 	ext{m/s}. $$How much time does it take to reach takeoff speed?

Accepted Answer

$$27\ 	ext{s}$$

Question 5

A ball is thrown downward from the top of a $$20\ 	ext{m}$$ building with an initial speed of $$3\ 	ext{m/s}. $$Ignoring air resistance, how long is it in the air? (Use $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$1.7\ 	ext{s}$$

Question 6

Which equation is valid for calculating displacement under constant acceleration?

Accepted Answer

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

Question 7

A fugitive starts from rest and accelerates at $$1.4\ 	ext{m/s}^2 to $$catch a train moving at $$5\ 	ext{m/s}. $$How long does it take her to catch up?

Accepted Answer

$$5.1\ 	ext{s}$$

Question 8

If the area under an acceleration-time graph between $$t_1$$ and $$t_2 is$$ $$8\ 	ext{m/s}$$, what does this represent?

Accepted Answer

The change in velocity over that interval

Question 9

A ball is thrown straight upward and hits the ground $$3\ 	ext{s}$$ after launch. What is the initial velocity? (Assume $$g = 9.8\ 	ext{m/s}^2$$ and the building is $$20\ 	ext{m}$$ tall.)

Accepted Answer

$$7.4\ 	ext{m/s}$$

Question 10

Which of the following is NOT a requirement for using the constant acceleration equations?

Accepted Answer

Initial velocity must be zero.

Question 11

A fan cart moves with zero acceleration. Which statement best describes its motion?

Accepted Answer

It moves at a constant velocity.

Question 12

A ball is thrown upward from a $$20\ 	ext{m}$$ building and reaches a maximum height above the ground. Which equation can be used to find the maximum height?

Accepted Answer

$$h_{max} = y_0$ + \frac{v_0$^2}{2g}$$

Question 13

A car skids to a stop with constant acceleration. Which graph best represents its velocity over time?

Accepted Answer

A straight line with negative slope

Question 14

A student throws a ball downward from a $$20\ 	ext{m}$$ building with an initial speed of $$3\ 	ext{m/s}. $$What is the velocity of the ball when it strikes the ground? (Use $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$20.7\ 	ext{m/s}$$

Question 15

A fugitive accelerates at $$1.4\ 	ext{m/s}^2 to $$her maximum speed of $$6.0\ 	ext{m/s}$$, then maintains that speed. If the train moves at $$5\ 	ext{m/s}$$, how long does it take her to catch up?

Accepted Answer

$$7.9\ 	ext{s}$$

Question 16

Which of the following best describes free fall near Earth's surface?

Accepted Answer

Objects accelerate downward at $$9.8\ 	ext{m/s}^2$$ regardless of their initial velocity.

Question 17

If an object is thrown upward, which statement about its acceleration is correct?

Accepted Answer

Acceleration is constant and directed downward.

Question 18

A runner increases her velocity from $$2\ 	ext{m/s} to$$ $$6\ 	ext{m/s} in$$ $$4\ 	ext{s}. $$What is her acceleration?

Accepted Answer

$$1\ 	ext{m/s}^2$$

Question 19

Which of the following is a real-world example of constant acceleration?

Accepted Answer

A car accelerating uniformly from a stoplight

Study Notes: Acceleration and Motion in One Dimension (Physics with Calculus)

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