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HW: Intro to Projectiles (Q3: Homework) Current Score : – / 48 1. –/1 points Due : Thursday, February 14 2013 11:59 PM EST

C hristopher Moehring Physics, section pd8 Instructor: Zhanna Glazenburg

A baseball dropped from the roof of a tall building takes 2 seconds to hit the ground. How tall is the building? [Neglect friction.] m

2. –/1 points

As a projectile moves through its parabolic trajectory, which of the following quantities does not remain constant? horizontal acceleration vertical velocity horizontal velocity vertical acceleration

3. –/1 points

A rock is dropped at the same instant that a ball at the same initial elevation is thrown horizontally. Which will have the greater speed when it reaches the ground? Both have the same speed The dropped rock The thrown ball

4. –/1 points

A projectile launched at an angle of 45o above the horizontal travels through the air. Compared to the projectiletheoretical path with no air friction, the actual trajectory of the projectile with air s friction is lower and shorter higher and longer lower and longer higher and shorter

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HW: Intro to Projectiles

5. –/1 points

The diagram below represents the path of a stunt car that is driven off a cliff, neglecting friction.

Compared to the horizontal component of the carvelocity at point A, the horizontal component of s the carvelocity at point B is s greater the same smaller

6. –/1 points

Two spheres, A and B, are simultaneously projected horizontally from the top of a tower. Sphere A has a horizontal speed of 40 meters per second and sphere B has a horizontal speed of 20 meters per second. Which statement best 2 describes the time required for the spheres to reach the ground and the horizontal distance they travel? [Neglect friction and assume the ground is level.] Both spheres hit the ground at the same time and at the same distance from the base of the tower. Sphere A hits the ground before sphere B, and sphere A lands twice as far as sphere B from the base of the tower. Both spheres hit the ground at the same time, but sphere B lands twice as far as sphere A from the base of the tower. Both spheres hit the ground at the same time, but sphere A lands twice as far as sphere B from the base of the tower.

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2/14/13

HW: Intro to Projectiles

7. –/3 points

A 3.5-kilogram block is dropped from the roof of a 36-meter tall building at the same time a 9.8kilogram ball is thrown horizontally from the same height at a speed horizontal velocity of 2.5 meters per second. Which statement best describes the motion of the block and the motion of the ball? [Neglect air resistance.] The block and the ball hit the ground at the same time because they have the same vertical acceleration. The 3.5-kg block hits the ground first because it has no horizontal velocity. The 9.8-kg ball hits the ground first because it is round. The 9.8-kg ball hits the ground first because it has more mass.

The time it takes a 3.5-kilogram block to it the ground is The horizontal range of the 9.8-kilogram ball is meters.

seconds.

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2/14/13

HW: Intro to Projectiles

8. –/3 points

A machine fired several projectiles at the same angle, θ, above the horizontal. Each projectile was fired with a different initial velocity, vi. The graph below represents the relationship between the magnitude of the initial vertical velocity, viy , and the magnitude of the corresponding initial velocity, vi, of these projectiles.

The magnitude of the initial vertical velocity of the projectile, viy , when the magnitude of its initial velocity, vi, was 40. meters per second is most nearly m/s. o

Determine the angle, θ, above the horizontal at which the projectiles were...