Question

H=120м v=10м/с найти:t

Answer 1

H = vt + gt^2/2
120=10t+5t^2; 5t^2+10t-120=0; t^2+2t-24=0
t1,2 = -6;4 
Ответ: 4 с.

Answer 2

To find the time (t) taken to reach a height (H) with an initial vertical velocity (v), you can use the following kinematic equation:

H = v*t + (1/2)gt^2

where: H = height (in meters) v = initial vertical velocity (in meters per second) t = time (in seconds) g = acceleration due to gravity (approximately 9.81 m/s^2 on Earth)

In this case, you are given: H = 120 meters v = 10 meters per second g = 9.81 m/s^2

Let's plug in the values and solve for t:

120 = 10*t + (1/2)9.81t^2

To make this equation easier to solve, let's first multiply everything by 2 to eliminate the fraction:

240 = 20t + 9.81t^2

Now, rearrange the equation to form a quadratic equation:

9.81t^2 + 20t - 240 = 0

Now, we can solve this quadratic equation for t. You can use the quadratic formula:

t = (-b ± √(b^2 - 4ac)) / 2a

where a = 9.81, b = 20, and c = -240.

t = (-(20) ± √((20)^2 - 4*(9.81)(-240))) / 2(9.81)

Now, calculate the discriminant:

√((20)^2 - 4*(9.81)*(-240)) = √(400 + 9417.6) = √9817.6 ≈ 99.08

Now, plug the discriminant back into the formula for t:

t = (-(20) ± 99.08) / 2*(9.81)

Now, find the two possible values of t:

t1 = (-(20) + 99.08) / 2*(9.81) ≈ 6.86 seconds t2 = (-(20) - 99.08) / 2*(9.81) ≈ -5.16 seconds

Since time cannot be negative in this context, the only valid solution for t is approximately 6.86 seconds.

So, it would take about 6.86 seconds to reach a height of 120 meters with an initial vertical velocity of 10 meters per second.