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Instantaneous rate of change: gradients of curves worksheet — GCSE Higher

Fifteen questions on "instantaneous rate of change: gradients of curves" — DfE statement R15. Print it, or print three versions so neighbours cannot copy by letter; the key gives the letter for each version.

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Instantaneous rate of change: gradients of curves worksheet — GCSE Higher

Maths · GCSE Higher · R15 · Instantaneous rate of change: gradients of curves · 15 questions

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1.The tangent to a curve at the point where x = 4 has equation y = 3x − 2. Work out the instantaneous rate of change of y with respect to x at x = 4.
y = 3x − 2
(a)−2
(b)4
(c)3
(d)10
2.A firework rocket's height above the ground, in metres, t seconds after launch, is modelled by h = 30t − 5t². Use a chord between t = 1 second and t = 3 seconds to estimate the instantaneous rate of change of the height at t = 2 seconds, in m/s.
(a)20
(b)−10
(c)35
(d)10
3.A cup of tea is cooling. Its temperature, in °C, is plotted against time, in minutes, since it was poured. At t = 4 minutes, the gradient of the tangent to the graph is −3.2. What does this tell you about the tea at t = 4 minutes?
(a)Temperature is 3.2°C
(b)Rising at 3.2°C per minute
(c)Falling at 3.2°C per minute
(d)Fallen 3.2°C in total so far
4.A shop's daily profit, in pounds, is plotted against the price charged for an item, in pounds. A tangent to the profit graph at a price of £15 passes through the points (12, 540) and (18, 480). Work out the instantaneous rate of change of profit with respect to price at £15, and state whether profit is increasing or decreasing there.
(a)Profit is increasing by £6 per £1 rise in price.
(b)Profit is increasing by £10 per £1 rise in price.
(c)Profit is decreasing by £60 per £1 rise in price.
(d)Profit is decreasing by £10 per £1 rise in price.
5.A curve has equation y = 2x² + 5. Work out an estimate for the gradient of the curve at x = 3, using a chord between the points where x = 2 and x = 4.
y = 2x² + 5
(a)25
(b)24
(c)0.08
(d)12
6.A tangent to a curve at the point where x = 3 passes through the points (1, 2) and (5, 14). A candidate says: "The gradient of the tangent at x = 3 is 3, because 14 − 2 = 12 and 12 ÷ 4 = 3." Which statement is correct?
(a)The gradient is 3; the candidate's method is right.
(b)The gradient is −3; the subtraction was done the wrong way round.
(c)The gradient is 16; the two changes were added instead of divided.
(d)The gradient is 1/3; the division was done the wrong way round.
7.A curve has equation y = x² + 2x. Work out the average rate of change of y with respect to x over the interval from x = 1 to x = 4.
y = x² + 2x
(a)7
(b)3
(c)21
(d)−7
8.The total cost, in pounds, of manufacturing a batch of components is plotted against the number of components produced. A tangent to this graph at a particular point has gradient 3.60. What does the value 3.60 represent?
(a)3.60% of the cost per component
(b)£3.60 total cost
(c)3.60 components per pound
(d)£3.60 per component
9.The height of a candle, in cm, is measured as it burns: t = 0 min, height = 20.0; t = 3 min, height = 18.7; t = 5 min, height = 17.5; t = 6 min, height = 16.6; t = 7 min, height = 15.4; t = 9 min, height = 13.4. Which pair of readings gives the best estimate of the instantaneous rate of change of the height at t = 6 minutes, and why?
(a)t = 0 and t = 6 (average from the start)
(b)t = 5 and t = 7 (closest, evenly spaced)
(c)t = 3 and t = 9 (wider interval, more data)
(d)t = 6 and t = 7 (next reading after 6)
10.The cost, in pounds, of hiring a minibus is modelled against the number of passengers booked. A tangent to the cost graph at 20 passengers passes through the points (16, 184) and (24, 216). Work out the instantaneous rate at which the cost increases with each extra passenger, at 20 passengers.
(a)£32
(b)£8
(c)£40
(d)£4
11.A tangent to the graph of population against time at the point where t = 4 passes through (2, 180) and (6, 260). Work out the instantaneous rate of change of the population at t = 4, in people per year.
(a)20 people/year
(b)84 people/year
(c)80 people/year
(d)−20 people/year
12.The temperature of a chemical reaction, in °C, is modelled by T = 80 − 6t + 0.5t², where t is the time in minutes after the reaction starts. Which of these four statements about the reaction between t = 2 and t = 6 minutes is correct?
(a)Instant rate at t = 6 is −2°C/min
(b)Instant rate at t = 2 is −2°C/min
(c)Average rate, t = 2 to 6, is −2°C/min
(d)Temperature falls 2°C in total
13.A greenhouse's temperature, in °C, is recorded every hour during the day: 09:00, 15.0; 10:00, 18.4; 11:00, 20.1; 12:00, 19.8; 13:00, 17.2. Work out between which two consecutive readings the instantaneous rate of change of the temperature is most likely to have been zero.
(a)11:00 to 12:00
(b)10:00 to 11:00
(c)09:00 to 10:00
(d)12:00 to 13:00
14.The height of a ball, in metres, above the ground is plotted against time, in seconds, after it is thrown. The tangent to the graph at t = 1.5 seconds has gradient 2. Which of these four statements about the ball at t = 1.5 seconds is correct?
(a)Height is 2 m at t = 1.5 s
(b)Speed is 2 m/s² at t = 1.5 s
(c)Height rising at 2 m/s at t = 1.5 s
(d)Ball travelled 2 m from t = 1 to t = 2 s
15.A cyclist's speed, in metres per second, is plotted against time, in seconds, since she sets off. Which statement correctly pairs the gradient of a tangent to this graph, and the area between the graph and the time-axis, with what each one represents?
(a)Gradient = distance travelled; area = acceleration.
(b)Gradient = speed itself; area = distance travelled.
(c)Gradient = acceleration; area = acceleration too.
(d)Gradient = acceleration; area = distance travelled.

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