A 873-kg (1930-lb) dragster, starting from rest completes a 405.0-m (0.2531-mile) run in 4.913 s. If the car had a constant acceleration, what would be its acceleration and final velocity?

Respuesta :

Weight of dragster = 873 kg

Distance traveled = 403.7 m

Time of travel = 4.920 s

Using the kinematic equation;

D=vt+1/2at^2

Answer:

Acceleration: approximately [tex]33.56\; {\rm m\cdot s^{-2}}[/tex].

Final velocity: approximately [tex]164.9\; {\rm m\cdot s^{-1}}[/tex].

Explanation:

Let [tex]x[/tex] denote displacement. Let [tex]a[/tex] denote the acceleration of the vehicle. Let [tex]t[/tex] denote the duration of the acceleration. Let [tex]u[/tex] denote the initial velocity of the vehicle.

In this question, it is given that [tex]x = 405.0\; {\rm m}[/tex], [tex]t = 4.913\; {\rm s}[/tex], and [tex]u = 0\; {\rm m\cdot s^{-1}}[/tex] since the vehicle started from rest. Acceleration [tex]a[/tex] is to be found.  

Since acceleration [tex]a[/tex] is constant, apply the SUVAT equation [tex]x = (1/2)\, a\, t^{2} + u\, t[/tex] and solve for acceleration [tex]a[/tex].

Note that since [tex]u = 0\; {\rm m\cdot s^{-1}}[/tex], the SUVAT equation becomes [tex]x = (1/2)\, a\, t^{2}[/tex].

Rearrange and solve this equation for [tex]a[/tex]:

[tex]\begin{aligned}a &= \frac{2\, x}{t^{2}} \\ &= \frac{2 \, (405.0\; {\rm m})}{(4.913\; {\rm s})^{2}} \\ &\approx 33.558\; {\rm m\cdot s^{-2}}\end{aligned}[/tex].

Let [tex]v[/tex] denote the velocity of the vehicle after the acceleration. Apply the SUVAT equation [tex]v = u + a\, t[/tex] to find this velocity:

[tex]\begin{aligned}v &= u + a\, t \\ &= (0\; {\rm m\cdot s^{-1}}) + (33.558\; {\rm m\cdot s^{-2}})\, (4.913\; {\rm s}) \\ &\approx 164.9\; {\rm m\cdot s^{-1}}\end{aligned}[/tex].