Question

solve each problem for speed, acceleration, momentum, energy, and heat. be sure to include si units and show your work.
s=d/t a=vf-vi/t p=mv pe= mgh
d= sxt vf= vi+a(t) m=p/v ke= 1/2mv²
t= d/s t=vf-vi/a v= p/m q=mc ▲ t

1. a plane travels 395,000 meters in 9,000 seconds. what was its speed?
2. in a competition, an athlete threw a flying disk 139 meters through the air. while in flight, the disk traveled at an average speed of 13.0 m/s. how long did the disk remain in the air?
3. a roller coaster car rapidly picks up speed as it rolls down a slope. as it starts down the slope, its speed is 4 m/s. but 3 seconds later, at the bottom of the slope, its speed is 22 m/s. what is its average acceleration?
4. if a ferrari, with an initial velocity of 10 m/s, accelerates at a rate of 50 m/s² for 3 seconds, what will its final velocity be?
5. a car traveling at a speed of 30 m/s encounters an emergency and comes to a complete stop. how much time will it take for the car to stop if it decelerates at -4 m/s²?

Explanation:

Problem 1

Step1: Identify formula for speed

We use the formula \( S=\frac{D}{T} \), where \( D = 395000 \) meters and \( T = 9000 \) seconds.

Step2: Substitute values into formula

\( S=\frac{395000}{9000}\approx43.89 \) m/s.

Step1: Identify formula for time

We use the formula \( T=\frac{D}{S} \), where \( D = 139 \) meters and \( S = 13.0 \) m/s.

Step2: Substitute values into formula

\( T=\frac{139}{13.0}\approx10.69 \) seconds.

Step1: Identify formula for acceleration

We use the formula \( A=\frac{V_f - V_i}{T} \), where \( V_i = 4 \) m/s, \( V_f = 22 \) m/s, and \( T = 3 \) seconds.

Step2: Substitute values into formula

\( A=\frac{22 - 4}{3}=\frac{18}{3}=6 \) m/s².

Answer:

The speed of the plane is approximately \( 43.9 \) m/s (or \( \frac{395}{9}\approx43.89 \) m/s).

Problem 2