Question

Тело бросили под углом 60° к горищонту с начальной скоростью 20 м/с. Через какое время t угол будет равен 45°

Answer 1

При угле 45 градусов проекции скоростей равны
vx/vy=tg45=1
vy=vx=v*cos60
t=vy/g=v*cos60/g=20*0.5/10=1 c
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Answer 2

Problem Analysis

We are given that an object is thrown at an angle of 60° to the horizontal with an initial velocity of 20 m/s. We need to find the time at which the angle of the object will be equal to 45°.

Solution

To solve this problem, we can use the equations of motion for projectile motion. The horizontal and vertical components of the initial velocity can be calculated using trigonometry:

Horizontal component of initial velocity (Vx) = v0 * cos(θ) Vertical component of initial velocity (Vy) = v0 * sin(θ) where v0 is the initial velocity and θ is the angle of projection.

Since the object is thrown at an angle of 60°, we can substitute the given values into the equations:

Vx = 20 m/s * cos(60°) = 20 m/s * 0.5 = 10 m/s Vy = 20 m/s * sin(60°) = 20 m/s * 0.866 = 17.32 m/s

Now, we can find the time at which the angle of the object will be equal to 45°. At this point, the vertical and horizontal components of velocity will be equal:

Vx = Vy

Substituting the values we calculated earlier:

10 m/s = 17.32 m/s * cos(45°) 10 m/s = 17.32 m/s * 0.707

Simplifying the equation:

10 m/s = 12.26 m/s

Since the equation is not satisfied, it means that the angle of 45° will not be reached by the object.

Therefore, there is no time at which the angle of the object will be equal to 45°.

Answer

There is no time at which the angle of the object will be equal to 45°.