8. The table shows some of the values of \(h = -3(t + 1)(t - 4)\) for \(0 \leqslant t \leqslant 5\).
\(t\)
0
1
2
3
4
5
\(h = -3(t + 1)(t - 4)\)
18
18
0
(a) Complete the table above. [2]
(b) On the graph paper below, draw the graph of \(h = -3(t + 1)(t - 4)\) for \(0 \leqslant t \leqslant 5\). [2]
(c)
Diagram not drawn to scale
Derek throws a ball upwards from a point above horizontal ground. The height, \(h\) metres, of the ball above the ground \(t\) seconds after Derek throws it is \(h = -3(t + 1)(t - 4)\).
(i) What is the height of the ball above the ground at the start of Derek’s throw? [1]
(ii) How many seconds after Derek throws the ball does it first hit the ground? [1]
(iii) How many seconds after Derek throws the ball is it at its maximum height? [1]
(iv) What is the maximum height of the ball above the ground? [1]
Mark scheme (a)
Scheme
Marks
Comments
\(t\)
0
1
2
3
4
5
\(h\)
12
18
18
12
0
\(-18\)
B2
B1 for any two correct
Mark scheme (b)
Scheme
Marks
Comments
All 6 correct points plotted correctly and joined with a smooth curve
B2
Mark intent
B1 for a smooth curve at least through 4 correct pairs of coordinates or for all of their 6 pairs of coordinates plotted correctly
Allow 2 marks here if curve correct even if there is a slip in their table
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