IB Physics Kinematics Practice Questions

Q: A car accelerates uniformly from rest and reaches $20\,\text{m s}^{-1}$ in $4\,\text{s}$. What is its acceleration?

$5\,\text{m s}^{-2}$. Use $a=\frac{\Delta v}{\Delta t}=\frac{20-0}{4}=5\,\text{m s}^{-2}$.

Q: An object is released from rest and falls freely for $3.0\,\text{s}$. Taking $g=9.8\,\text{m s}^{-2}$, how far does it fall?

$44\,\text{m}$. Use $s=ut+\frac{1}{2}gt^{2}=0+\frac{1}{2}(9.8)(3.0)^{2}=44.1\,\text{m}$.

Q: A ball is thrown vertically upward at $15\,\text{m s}^{-1}$. Taking $g=9.8\,\text{m s}^{-2}$, what is the maximum height reached?

$11.5\,\text{m}$. At the top $v=0$, so $v^{2}=u^{2}-2gs$ gives $0=15^{2}-2(9.8)s$, hence $s=\frac{225}{19.6}=11.5\,\text{m}$.

Q: A runner completes exactly one lap of a $400\,\text{m}$ circular track, finishing where they started. What is their displacement?

$0\,\text{m}$. Displacement is the straight-line change in position. Returning to the start gives a displacement of zero, even though the distance travelled is $400\,\text{m}$.

Q: A cyclist travels $100\,\text{m}$ at constant velocity in $20\,\text{s}$. Their speed is _____ $\text{m s}^{-1}$.

5 / 5.0. Speed $=\frac{\text{distance}}{\text{time}}=\frac{100}{20}=5\,\text{m s}^{-1}$.

Question 1

A car accelerates uniformly from rest and reaches $20\,	ext{m s}^{-1}$ in $4\,	ext{s}$. What is its acceleration?

Accepted Answer

$5\,	ext{m s}^{-2}$. Use $a=\frac{\Delta v}{\Delta t}=\frac{20-0}{4}=5\,	ext{m s}^{-2}$.

Question 2

An object is released from rest and falls freely for $3.0\,	ext{s}$. Taking $g=9.8\,	ext{m s}^{-2}$, how far does it fall?

Accepted Answer

$44\,	ext{m}$. Use $s=ut+\frac{1}{2}gt^{2}=0+\frac{1}{2}(9.8)(3.0)^{2}=44.1\,	ext{m}$.

Question 3

A ball is projected horizontally from a cliff. Ignoring air resistance, which quantity stays constant during the flight?

Accepted Answer

The horizontal component of velocity. The horizontal velocity is unchanged because no horizontal force acts; gravity only changes the vertical velocity.

Question 4

A ball is thrown vertically upward at $15\,	ext{m s}^{-1}$. Taking $g=9.8\,	ext{m s}^{-2}$, what is the maximum height reached?

Accepted Answer

$11.5\,	ext{m}$. At the top $v=0$, so $v^{2}=u^{2}-2gs$ gives $0=15^{2}-2(9.8)s$, hence $s=\frac{225}{19.6}=11.5\,	ext{m}$.

Question 5

A runner completes exactly one lap of a $400\,	ext{m}$ circular track, finishing where they started. What is their displacement?

Accepted Answer

$0\,	ext{m}$. Displacement is the straight-line change in position. Returning to the start gives a displacement of zero, even though the distance travelled is $400\,	ext{m}$.

Question 6

On a velocity-time graph for motion in a straight line, the area between the line and the time axis represents which quantity?

Accepted Answer

Displacement. The area under a velocity-time graph equals displacement, since $v	imes t$ has units of metres.

Question 7

For uniform acceleration, the equation linking final velocity, initial velocity $u$, acceleration $a$ and time $t$ is $v=$ _____.

Accepted Answer

u+at / u + at. This is the first SUVAT equation, $v=u+at$, obtained directly from the definition of constant acceleration.

Question 8

A cyclist travels $100\,	ext{m}$ at constant velocity in $20\,	ext{s}$. Their speed is _____ $	ext{m s}^{-1}$.

Accepted Answer

5 / 5.0. Speed $=\frac{	ext{distance}}{	ext{time}}=\frac{100}{20}=5\,	ext{m s}^{-1}$.

Question 9

An object starts from rest and undergoes constant acceleration a. Which graph yields a straight line through the origin whose gradient is a/2?

Accepted Answer

displacement against time squared. Since s = (1/2) a t squared, s against t squared is linear with gradient a/2.

Question 10

For an object starting from rest with uniform acceleration, the displacement is proportional to

Accepted Answer

the square of the time. From s = (1/2) a t squared, displacement is proportional to the square of the time.

IB Physics: Kinematics — Practice Questions & Answers

Practice questions with answers

Ready to test yourself?

Practise other IB Physics topics