# Physics

posted by .

In running the 40 m dash in tryouts fot the Notre Dame football team, Zach S. completes the 40 m in 4.8 seconds. Assuming constant acceleration throughout the run, find his velocity at the end of 40 m and his acceleration during the 40 m.

• Physics -

For the acceleration a, solve
X = (1/2) a t^2

a = 2X/t^2 = 3.472 m/s^2

For the velocity after 4.8 seconds, solve
V = a t

You will get a number that is higher than the world record average speed for the 100 m dash. I do not believe the figures. The problem is probably the assumption that constant acceleration can be maintained for 40 meters.

• Physics -

You know, if you have a problem with time, acceleration, velocity and distance, before bothering to post the question, try using the formulas you know and love:

v = at
s = 1/2 at^2

Since there is constant acceleration,

s = 1/2 at^2
40 = 1/2 a * 4.8^2
a = 3.47222 m/s^2

v = at = 3.47222 * 4.8 = 16.67 m/s

## Similar Questions

1. ### physics

A football is thrown horizontally with an initial velocity of (16.5 m/s). Ignoring air resistance, the average acceleration of the football over any period of time is (-9.81 m/s2). (a) Find the velocity vector of the ball 1.62 s after …
2. ### college physics

i need solutions for all this problems...help please.... 1.) an electron moving at a speed of 4x10 power of 6 m/s, shot through a sheet of paper which is 3x10 to power of -5 m thick. the electron energyfrom the sheet with with a speed …
3. ### Notre Dame

I have a question that is still not homework-related, even on my first day of school today. What's up with the school name known as "Notre Dame"?
4. ### AP Physics

An experimental rocket car starting from rest reaches a speed of 600 km/h after a straight 370 m run on a level salt flat. Assuming that acceleration is constant, answer the following questions. a)What was the time of the run?
5. ### physics

A 873-kg (1930-lb) dragster, starting from rest completes a 403.7-m (0.2523-mile) run in 4.920 s. If the car had a constant acceleration, what would be its acceleration and final velocity?
6. ### Physics

(a) In 2009, Usain Bolt ran the last 100 meters of the 150-meter race in 8.70 seconds. What is Usain Boltâ€™s speed?
7. ### Physics

The first meters of a 100-meter dash are covered in 2 seconds by a sprinter who starts from rest and accelerates with a constant acceleration. The remaining 90 meters are run with the same velocity the sprinter had after 2 seconds. …
8. ### Physics

A car starts from rest and travels for 10 seconds with a constant acceleration of 3.0 m s^-2. The driver then applies the brakes causing a negative acceleration of -4.0 m s^-2. Assuming that the brakes are applied for 2.0 seconds, …
9. ### physics

A 873-kg (1930-lb) dragster, starting from rest completes a 403.6-m (0.2523-mile) run in 4.935 s. If the car had a constant acceleration, what would be its acceleration and final velocity?
10. ### physics

Given the graph below with the initial velocity, vi = -8 m/s, the object starts with one value of constant acceleration and stops at 2.3 seconds. Then, the value of its acceleration changes to a different acceleration. Finally, at …

More Similar Questions