187k views
3 votes
The 2020 Ford police interceptor has a max acceleration of 4.4 m/s2. If a policeperson is sitting on

the roadside when a speeding car passes them at 70 mph (31.3 m/s), and the policeperson takes off
at max acceleration 1 second later, will they be able to catch the speeder in 10 seconds?
(Show work)

User Dwenaus
by
5.0k points

1 Answer

4 votes

Answer:

The policeperson will not be able to catch the speeder in 10 seconds

Step-by-step explanation:

The maximum acceleration of the 2020 Ford police interceptor, a = 4.4 m/s²

The rate at which the speeding car is moving, v = 70 mph (31.3 m/s)

The time after which the policeperson takes off = 1 second

The time, t, at which the policeperson catches the speeding car is given as follows;

s = u·t + 1/2·a·t²

Where;

u = The initial velocity of the Ford police interceptor = 0

∴ s = 0 × t + 1/2·a·t² = 1/2·a·t²

s = 1/2·a·t²

s = v × (t + 1)

Equating both equations, gives;

v × (t + 1) = 1/2·a·t²

Substituting the values, we get;

31.3 × (t + 1) = 1/2 × 4.4 × t²

31.3·t + 31.3 = 2.2·t²

2.2·t² - 31.3·t - 31.3 = 0

By the quadratic formula, we have;

t = (31.3 ± √((-31.3)² - 4×2.2×(-31.3))/(2 × 2.2)

t ≈ -0.938 seconds or t ≈ 15.165 seconds

The policeperson will catch the speeder in approximately 15.165 seconds

Therefore, the policeperson will not be able to catch the speeder in 10 seconds.

User ShivRaj
by
4.8k points