Changing The Subject

The formulas below have been rearranged, some are correct and others are wrong. Decide which are right and which are wrong and be prepared to explain why. The first one has been done for you.

1.     Distance time formula:  $s = ut + \frac{1}{2}at^2$

(s = distance,  u = initial velocity, a = acceleration, t =time).

(A)  $u = \frac{s}{t} – \frac{1}{2}at {\checkmark}$                     (B)   $a = \frac{s-ut}{t^2} {\sf X}$

2.   Velocity time formula: $v = u + at$

(v  = velocity at time t, u = initial velocity, a  = acceleration, t = time)

(A) $u = v-at$       (B)  $t = a(v +u)$       (C) $a = \frac {v-u}{t}$

3.    Ohm’s Law: $V = IR$

(V= voltage,  I = current, R = resistance)

(A) $I = VR$       (B) $ r = \frac {V}{I}

4.   Boyle’s Law: $PV=C$  where C is constant. At constant temperature, the volume of a fixed amount of a gas $V$ is inversely proportional to its pressure $P$.

(A)  $V=\frac{P}{C}$       (B)  $P=VC$

5.   Newton’s 2^nd law of motion:  $F = ma$ 

(F = Force,  m = mass,  a = acceleration).

(A)    $a = Fm$       (B)  $m =\frac{F}{a}$

6.    Einstein’s Law:  $E = mc^2$

(E = energy, m = mass,  c  = the speed of light).

The equation revealed that mass and energy are different forms of the same thing.

(A)   $c = \frac{E}{m}$       (B)  $c =\sqrt{\frac{E}{m}}$       (C) $m = Ec^2$

Make up your own similar questions based on these 4 formulas:

Parabola: $y^2=cx$  for constant c.

Rectangular hyperbola: $xy=c$     for constant c.

Circle (radius r):  $x^2 + y^2 = r^2$  

Ellipse: $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$