Fill in the values given for u, v, a, s and t in their standard units: 144 km h1 40 m s1 and 36 km h1 10 m s1 u 40 m s1 v 10 m s1 a s 75 m t
3 3 EXERCISE 2.3 UVAST
Q1 An aircraft was travelling at a speed of 60 m s1 when it landed on the runway. It took 2 minutes to stop. Calculate the average acceleration of the aircraft while coming to a stop.
Q2 A snake can accelerate its head at 8 m s2.What is the shortest length of time it will take the snake, starting from rest, to strike a mouse, which is 1 m from its head?
Q3 How far will a car travel when decelerating uniformly at 5 m s2 from 30 m s1 to 8 m s1? How long will the deceleration take?
Q4 A car accelerates at 3 m s2 up to a speed of 15 m s1 over 36 m.What was the car’s initial velocity?
Q5 A motorcycle accelerates from 10 m s1 to 40 m s1 in 8 s. Calculate: (i) the average acceleration of the bike
Distance–Time Graphs
Plotting a graph of distance from a given point against time can be useful in illustrating different types of motion. We are primarily interested in constant velocity graphs, because we can use our knowledge of co-ordinate geometry to calculate velocity using the slope of the graph.
The slope of a distance–time graph is equal to the velocity. slope
y2 y1 x2 x1
s2 s1 t2 t1
Constant velocity
s t v
We must also be able to recognise other types of motion based on their distance–time graphs.
Acceleration Deceleration (ii) distance travelled during that time
Calculating its acceleration: v 2 u 2 2as Fill in the values given:
The body is decelerating at 10 m s2. Qa 1 500
(10)2 (40)2 2a(75)Q100 1 600 150a 150 10
Time / s a = 0
Time / s a > 0
Fig 2.17: Diagram of distance–time graphs LINEAR MOTION 25
