A car is moving along a straight horizontal road, with a constant acceleration. The car passes point A, with a speed of ums(-1). 10 seconds later, passes point B, with a speed of 45 ms(-1). The distance from A to B is 300m. Find u.
Here, we must consider our UVAST equations of motion, and our variables.
U=?ms^(-1), V=45ms^(-1) , A=?ms^(-2), S= 300m, T=10s
Our equations of motion are:
V = U + AT , S = (1/2)(V+U)T , S = UT + (1/2)AT^2 , V^2 = U^2 + 2AS
We know, V, S and T. And want to find U.
The right equation to find U is therefore S = (1/2)(V+U)T
Re-arranging we have: ((2)(S)/T ) - V = U
Therefore = ((2 * 300 ) / 10 ) - 45 = U
Therefore U = 15ms^(-1)
AM
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