Question

Шайба массой 150 г, летящая горизонтально со скоростью 20 м/с, ударяется о борт под углом 30 градусов и отскакивает от него. Определить среднюю силу удара шайбы о борт. Продолжительность удара 0.02 с

Answer 1

Направим ось Х перпендикулярно стенке,а ось У-вертикально вверх.По второму закону Ньютона в векторной форме импульс силы: Ft=m(v2-v1);Или в проекциях на оси Х и У:

v1х=-v1cosa=-vcosa;v2x=v2cosa=vcosa;v1y=vsina,v2y=-vsinaа;

(Ft)x=m(vcosa+vcosa)=2mvcosa; (Ft)y=m(-vsina+vsina)=0;

F=2*mvcosa;t=2*mvcosa/t;

F=2*0.15*20*0.87/0.02=261H

Answer 2

Given Information:

- Mass of the puck (m): 150 g = 0.15 kg - Initial horizontal velocity of the puck (v): 20 m/s - Angle of collision with the board (θ): 30 degrees - Duration of impact (t): 0.02 s

Approach:

To determine the average force of impact, we can use the impulse-momentum principle. The impulse experienced by an object is equal to the change in momentum it undergoes. The average force of impact can be calculated using the equation:

Impulse = Average Force × Duration of Impact

The impulse can be calculated as the change in momentum of the puck before and after the collision. Let's break down the calculation into steps.

Step 1: Initial Velocity Components

First, we need to determine the initial velocity components of the puck in the horizontal and vertical directions. Since the puck is flying horizontally, the initial vertical velocity component is zero.

Horizontal Initial Velocity (v_x) = v × cos(θ) Vertical Initial Velocity (v_y) = v × sin(θ)

Step 2: Final Velocity Components

Next, we need to calculate the final velocity components of the puck after the collision. Since the puck rebounds and changes direction, the vertical component of the final velocity will have the same magnitude but in the opposite direction.

Horizontal Final Velocity (v'_x) = v_x Vertical Final Velocity (v'_y) = -v_y

Step 3: Change in Momentum

The change in momentum of the puck can be calculated by subtracting the initial momentum from the final momentum.

Horizontal Change in Momentum (Δp_x) = m × v'_x - m × v_x Vertical Change in Momentum (Δp_y) = m × v'_y - m × v_y

Step 4: Impulse

The impulse experienced by the puck is the vector sum of the horizontal and vertical components of the change in momentum.

Impulse = √(Δp_x² + Δp_y²)

Step 5: Average Force of Impact

Finally, we can calculate the average force of impact by dividing the impulse by the duration of impact (t).

Average Force = Impulse / t

Let's calculate the values using the given information.