2º EM - BALLISTIC: OBLIQUE LAUNCHING

Students, continuing our studies of ballistics, we will, in today's class, do tests involving oblique throws. To do this, go to the link below:

https://phet.colorado.edu/sims/html/projectile-motion/latest/projectile-motion_pt_BR.html

After accessing, enter the last icon: Lab. Place the cannon at a 25° angle. Select a 0.5 m diameter cannonball, mass 10 kg, turn off air resistance, select a velocity of 16 m/s and fire the cannon (red icon at the bottom). Measure horizontal reach, maximum height reached and movement time. Keeping the cannonball and launch velocity, repeat the procedure for the slopes indicated in the table below.

ANGLE	MAX. HEIGHT	HORIZ. REACH	TIME
25°
30°
35°
40°
44°
45°
46°
50°
55°
60°
65°
70°
80°
85°
90°

Questions:

For which slope does the maximum range occur?

For which slope does the maximum height occur?

What happens when we compare the ranges of complementary slopes?

Changing the bullet mass to 30 kg and keeping the other parameters, complete the table below:

ANGLE	MAX. HEIGHT	HORIZ. REACH	TIME
30°
45°
60°
90°

Changing the bullet diameter to 1.0 m and keeping the other parameters from the initial situation (m = 10 kg, v = 16 m/s, without air R.), complete the table below:

ANGLE	MAX. HEIGHT	HORIZ. REACH	TIME
30°
45°
60°
90°

Compare tables 1, 2 and 3 and draw conclusions.

Now putting air resistance, complete tables like above for the following situations:

a-) m = 10 kg, d = 0.5 m, v = 10 m/s and v = 16 m/s (2 tables)

b-) m = 10 kg, d = 1.0 m, v = 10 m/s and v = 16 m/s (2 tables)

c-) m = 30 kg, d = 0.5 m, v = 10 m/s and v = 16 m/s (2 tables)

d-) m = 30 kg, d = 1.0 m, v = 10 m/s and v = 16 m/s (2 tables)

CONCLUSIONS:

2º EM - Atividade Impulso e Quantidade de movimento

 ATIVIDADE DE IMPULSO E QUANTIDADE DE MOVIMENTO

1-) Uma força constante atua durante 5,0 s sobre uma partícula de massa 2,0 kg, na direção e no sentido de seu movimento, fazendo com que sua velocidade varie de 5,0 m/s para 9,0 m/s. Determine:

a-) o módulo da variação da quantidade de movimento da partícula;

b-) a intensidade do impulso da força atuante;

c-) a intensidade da força.

2-) um corpo de massa m = 10 kg possui velocidade v1 de direção horizontal e intensidade 3 m/s. Recebe um impulso I de uma força F que altera sua velocidade inicial v1 para v2 perpendicular a v1 e de intensidade igual a 4 m/s. Determine o impulso I dessa força F.

3-) Um projétil de massa 20 g incide horizontalmente sobre uma tábua com velocidade de 500 m/s e a abandona com velocidade horizontal e de mesmo ssentido de valor 300 m/s. Qual a intensidade do impulso aplicado ao projétil pela tábua?

4-) Um corpo é lançado verticalmente para cima com velocidade inicial de 20 m/s. Sendo 5,0 kg a massa do corpo, determine a intensidade do impulso da força-peso entre o instante inicial e o instante em que o corpo atinge o ponto mais alto da trajetória

5-) Sobre um corpo de massa 3,0 kg, movendo-se a 5,0 m/s, age uma força de maneira que, após 10 s, sua velocidade tem o valor de 2,0 m/s em sentido oposto ao inicial. Qual o valor da intensidade da força que atuou sobre esse corpo?

6-) Um carrinho de massa 100 g encontra-se em repouso quando nele passa a atuar uma força resultante F de direção constante e cuja intensidade varia com o tempo conforme o gráfico. Determine:

a-) a intensidade do impulso da fora F no intervalo de tempo de 0 a 1,0 s;

b-) a velocidade do carrinho no instante 2,0 s.

2º EM - Laboratory: Horizontal Launch

 One of the great branches of Physics, studied since the beginning of human history, is the movement of projectiles called Ballistics. They involve projectile launch in 3 situations: when the launch is made in the vertical direction (the velocity only has a vertical component), when the initial velocity has only a horizontal component and when the initial velocity has both vertical and horizontal components (called oblique launch). In today's class we will work with horizontal releases. To do this, go to the link below:

https://phet.colorado.edu/sims/html/projectile-motion/latest/projectile-motion_pt_BR.html

1. After accessing the link, enter the second icon: vectors. Click on the " + " sign at the base of the cannon and raise it until it reaches 15 m and place the cannon horizontally (0° inclination). Select a 0.2 m diameter, 2 kg mass cannonball, turn off air resistance, select a velocity of 10 ms-1 and fire the cannon (red icon at the bottom). Measure horizontal range and movement time. Repeat the procedure for speeds of 15 m/s and 18 m/s.

Questions:

Has the horizontal range changed?

Has the movement time changed?

Has the vertical component of velocity changed?

CONCLUSIONS:

2. Change the height to 12 m, launch with speeds of 10 m/s, 15 m/s and 18 m/s. Measure horizontal range and movement time. Compare with previous results and draw conclusions.

3. a Return the cannon to a height of 15 m, quadruple the bullet diameter and repeat the procedure for a velocity of 18 m/s. Comparing the two situations, was there any change in movement time? And in the horizontal range?

3. b Return the diameter to 0.2 m and quadruple the bullet's mass. Repeat the procedure for the speed of 18 m/s. Comparing the results for this situation and the initial one, was there a change in the movement time? And in the horizontal range?

CONCLUSIONS:

4. Go back to the starting bullet (0.2 m and 2 kg) but now add air resistance.

a. Make throws at 5 m/s, 10 m/s and 15 m/s, noting movement time and horizontal reach.

b. Triple the bullet diameter and repeat this procedure.

c. Return to 0.2 m in diameter and triple the bullet's mass, repeating the procedure used in the two previous situations.

QUESTIONS:

Does fall time depend on launch speed?

Does the fall time depend on the diameter of the bullet?

Does the fall time depend on the bullet's mass?

CONCLUSIONS: