Motion & Kinematics

Describing motion with graphs, SUVAT equations and projectile decomposition.

Spec Points Covered
  • I can define and distinguish between displacementThe distance moved in a particular direction from a starting point. A vector quantity. Measured in metres (m)., velocityThe rate of change of displacement. A vector quantity. Measured in m s⁻¹., speed and accelerationThe rate of change of velocityThe rate of change of displacement. A vector quantity. Measured in m s⁻¹.. A vector quantity. Measured in m s⁻². as scalar or vector quantities.
  • I can interpret displacementThe distance moved in a particular direction from a starting point. A vector quantity. Measured in metres (m).-time graphs to find velocityThe rate of change of displacement. A vector quantity. Measured in m s⁻¹. from the gradient.
  • I can interpret velocity-time graphs to find accelerationThe rate of change of velocity. A vector quantity. Measured in m s⁻². (gradient) and displacementThe distance moved in a particular direction from a starting point. A vector quantity. Measured in metres (m). (area under graph).
  • I can interpret accelerationThe rate of change of velocity. A vector quantity. Measured in m s⁻².-time graphs and determine change in velocity from the area under the graph.
  • I can select and apply the correct SUVAT equation to problems involving uniform acceleration.
  • I can solve multi-stage SUVAT problems where the final velocity of one stage becomes the initial velocity of the next.
  • I can describe free fallMotion under gravity alone, with no other forces acting. All objects in free fall near Earth's surface have the same acceleration, g = 9.81 m s⁻². and use g = 9.81 $m s^{-2}$ in calculations, including objects thrown upwards.
  • I can resolve projectileAn object moving freely under gravity after being launched. Horizontal and vertical components of motion are independent. motion into independent horizontal and vertical components.
  • I can calculate the range, maximum height and time of flight for a projectileAn object moving freely under gravity after being launched. Horizontal and vertical components of motion are independent..
  • I can describe experiments to measure the acceleration due to gravity.
Notes
01 Displacement Displacement → 02 The gradient of a displacement-time graph gives the velocity → 03 The gradient of a velocity-time graph gives the acceleration → 04 The SUVAT equations apply only to motion with constant (uniform) acceleration $v = u + at$ → 05 Free fall Free fall → 06 Projectile Projectile → 07 The area under an acceleration-time graph gives the change in velocity →
Σ Key Equations Full Reference →
On Data Sheet
Not on Data Sheet
First SUVAT equation
$$v = u + at$$
  • Where:
    • $v$ = m \(s^{-1}\)
    • $u$ = m \(s^{-1}\)
    • $a$ = m \(s^{-2}\)
    • $t$ = s
Use when you know u, a, t and want v (or rearrange). No s in this equation.
Second SUVAT equation
$$s = ut + \frac{1}{2}at^{2}$$
  • Where:
    • $s$ = m
    • $u$ = m \(s^{-1}\)
    • $a$ = m \(s^{-2}\)
    • $t$ = s
Use when you know u, a, t and want s. No v in this equation.
Third SUVAT equation
$$v^{2} = u^{2} + 2as$$
  • Where:
    • $v$ = m \(s^{-1}\)
    • $u$ = m \(s^{-1}\)
    • $a$ = m \(s^{-2}\)
    • $s$ = m
Use when you know u, a, s and want v, or when time is not given. No t in this equation.
Fourth SUVAT equation
$$s = \frac{(u + v)}{2} \times t$$
  • Where:
    • $s$ = m
    • $u$ = m \(s^{-1}\)
    • $v$ = m \(s^{-1}\)
    • $t$ = s
Displacement equals average velocity times time. No a in this equation.
Horizontal component of velocity
$$v_{x} = u\cos\theta$$
  • Where:
    • $v_x$ = m \(s^{-1}\)
    • $u$ = m \(s^{-1}\)
Used in projectile problems. The horizontal velocity is constant throughout the flight (no horizontal acceleration).
Vertical component of velocity
$$v_{y} = u\sin\theta$$
  • Where:
    • $v_y$ = m \(s^{-1}\)
    • $u$ = m \(s^{-1}\)
Used in projectile problems. The vertical velocity changes due to gravitational acceleration g.
Average velocity
$$\bar{v} = \frac{\Delta s}{\Delta t}$$
  • Where:
    • $\bar{v}$ = m \(s^{-1}\)
    • $\Delta s$ = m
    • $\Delta t$ = s
Average velocity equals total displacement divided by total time.