Physics, 19.12.2019 11:31 lisa5250

Two students are on a balcony 19.6 m above the street. one student throws a ball vertically downward at 14.7 m/s; at the same instant, the other student throws a ball ver- problems 53 tically upward at the same speed. the second ball just misses the balcony on the way down. (a) what is the difference in the two ballsâ time in the air? (b) what is the velocity of each ball as it strikes the ground? (c) h

Answers: 3

Show answers

Answers

Answer from: luludawn2455

a) Time difference in ball hitting ground in 2 cases = 3 seconds.

b) Velocity of both balls hitting ground is same, which is equal to 24.5 m/s.

Explanation:

We have equation of motion , $s= ut+\frac{1}{2} at^2$ , s is the displacement, u is the initial velocity, a is the acceleration and t is the time.

a) Let the upward direction be negative and downward direction be positive. Now considering the case where student throws downward.

We have u = 14.7 m/s, acceleration = acceleration due to gravity = 9.8 m/s^2 , we need to find time when s = 19.6 m.

$19.6=14.7*t+\frac{1}{2} *9.8*t^2\\ \\ t^2+3t-4=0\\ \\ (t-1)(t+4)=0$

So we will get t = 1 seconds or t = -4 seconds(not possible)

So ball reaches ground after 1 second when thrown downward with velocity 14.7 m/s.

Now considering the case where student throws downward.

We have u = -14.7 m/s, acceleration = acceleration due to gravity = 9.8 m/s^2 , we need to find time when s = 19.6 m.

$19.6=-14.7*t+\frac{1}{2} *9.8*t^2\\ \\ t^2-3t-4=0\\ \\ (t+1)(t-4)=0$

So we will get t = 4 seconds or t = -1 seconds(not possible)

So ball reaches ground after 4 second when thrown upward with velocity 14.7 m/s.

Time difference = 4 - 1 = 3 seconds.

b) We have equation of motion, v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration and t is the time taken.

Now considering the case where student throws downward.

We have u = 14.7 m/s, acceleration = acceleration due to gravity = 9.8 m/s^2 , and t = 1 second.

v = 14.7 + 9.8 * 1 = 24.5 m/s

So ball thrown downward with velocity 14.7 m/s strikes ground at 24.5 m/s.

Now considering the case where student throws downward.

We have u = -14.7 m/s, acceleration = acceleration due to gravity = 9.8 m/s^2 , and t = 4 second.

v = -14.7 + 9.8 * 4 = 24.5 m/s

So ball thrown upward with velocity 14.7 m/s strikes ground at 24.5 m/s.

Answer from: Quest

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000

Answer from: Quest

Independent variable is something that is changed in a experiment.

Other questions on the subject: Physics

Physics, 21.06.2019 17:30, nana54muller

Acatapult is tested by roman legionnaires. they tabulate the results in a papyrus and 2000 years later the archaeological team reads (distances translated into modern units): range = 0.4 km; angle of launch = π/5 rad; landing height = launch height. what is the initial velocity of launch of the boulders if air resistance is negligible?

Answers: 3

continue

Physics, 21.06.2019 18:00, justhereforanswers13

According to the law of conservation of mass, in a chemical reaction the total starting mass of all the reactants equal the total final mass of all the products. true or false?

Answers: 1

continue

Physics, 21.06.2019 20:10, FinnaCryDotJpeg

Which force is most responsible for binding together an atom's protons and neutrons? electrostatic gravitational nuclear magnetic

Answers: 1

continue

Physics, 21.06.2019 21:30, spycn7717

Apendulum has a mass of 1.5 kg and starts at a height of 0.4 m. if it is released from rest, how fast is it going when it reaches the lowest point of its path? acceleration due to gravity is g = 9.8 m/s2. a. 2.8 m/s b. 0 m/s c. 5.9 m/s d. 4.3 m/s

Answers: 1

continue

You know the right answer?

Two students are on a balcony 19.6 m above the street. one student throws a ball vertically downward...