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a is always perpendicular to v x a is always perpendicular to v y

The vector r indicates the instantaneous displacement of a projectile from the origin. At the instant when the projectile is at r, its velocity and acceleration vectors are v and a . Which statement is correct? Select the correct answer. a is always perpendicular to v x

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a is always perpendicular to v x a is always perpendicular to v y

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  1. The vector r indicates the instantaneous displacement of a projectile from the origin. At the instant when the projectile is at r, its velocity and acceleration vectors are v and a. Which statement is correct? Select the correct answer. • a is always perpendicular to vx • a is always perpendicular to vy • a is always perpendicular to v • a is always perpendicular to r • v is always perpendicular to r

  2. The speed of a particle moving in a circle 7.5m in radius increases at the constant rate of 5.0 m/s2. At an instant when the magnitude of the total acceleration is 8.4 m/s2 what is the speed of the particle? Select the correct answer. • 7.1 m/s • 8.6 m/s • 5.0 m/s • 7.9 m/s • 6.1 m/s

  3. A ball is thrown horizontally from the top of a building 0.11 km high. The ball strikes the ground at a point 65m horizontally away from and below the point of release. What is the speed of the ball just before it strikes the ground? Select the correct answer. • 48 m/s • 46 m/s • 14 m/s • 60 m/s • 33 m/s

  4. A baseball is hit at ground level. The ball is observed to reach its maximum height above ground level 4.6s after being hit. And 3.1s after reaching this maximum height, the ball is observed to barely clear a fence that is 68.0m from where it was hit. How high is the fence? Select the correct answer. • 56.6 m • 78.6 m • 2.2 m • 24.3 m • 13.2 m

  5. A rock is projected from the edge of the top of a building with an initial velocity of 16.6m/s at an angle of 53°, above the horizontal. The rock strikes the ground a horizontal distance of 56.4m from the base of the building. Assume that the ground is level and that the side of the building is vertical. How tall is the building? Select the correct answer. • 81.3 m • 62.5 m • 90.3 m • 46.2 m • 99.3 m

  6. A student in the front of a school bus tosses a ball to another student in the back of the bus while the bus is moving forward at constant velocity. The speed of the ball as seen by a stationary observer in the street _____ . Select the correct answer. • may be either greater, smaller, or equal to that observed inside the bus • is the same as that observed inside the bus • may be either greater or smaller than that observed inside the bus • is less than that observed inside the bus • is greater than that observed inside the bus

  7. A race car moving with a constant speed of 72m/s completes one lap around a circular track in 62s. What is the magnitude of the acceleration of the race car? Select the correct answer. • 7.3 m/s2 • 1.2 m/s2 • 2.3 m/s2 • 5.4 m/s2 • 9.1 m/s2

  8. A 0.22-km wide river has a uniform flow speed of 5.5 m/s toward the east. A boat with a speed of 9.6 m/s relative to the water leaves the south bank and heads in such a way that it crosses to a point directly north of its departure point. How long does it take the boat to cross the river? Select the correct answer. • 28 s • 23 s • 20 s • 15 s • 54 s

  9. At the lowest point in a vertical dive (radius = 0.69 km), an airplane has a speed of 380 km/h which is not changing. Determine the magnitude of the acceleration of the pilot at this lowest point. Select the correct answer. • 16 m/s2 • 21 m/s2 • 2.6 m/s2 • 28 m/s2 • 6.5 m/s2

  10. A particle starts from the origin at t = 0 with a velocity of (13i -10j) m/s and moves in the xy plane with a constant acceleration of a = (5.2i - 8.2j)m/s2 What is the speed of the particle at t = 3.8s? Select the correct answer. • 53 m/s • 39 m/s • 74 m/s • 23 m/s • 59 m/s

  11. A particle moves in the xy plane with a constant acceleration given by a = -1.8j m/s2. At t = 0. its position and velocity are 40i m and (-8.7i + 2.8j) m/s. respectively. What is the distance from the origin to the particle at t = 8.6s? Select the correct answer. • 55 m • 86 m • 42 m • 35 m • 46 m

  12. A projectile is thrown from the top of a building with an initial velocity of 11 m/s in the horizontal direction. If the top of the building is 10 m above the ground, how fast will the projectile be moving just before it strikes the ground? Select the correct answer. • 18 m/s • 25 m/s • 14 m/s • 16 m/s • 15 m/s

  13. An airplane flies horizontally with a speed of 300 m/s at an altitude of 390 m. Assume that the ground is level. At what horizontal distance from a target must the pilot release a bomb so as to hit the target? Select the correct answer. • 2.7 km • 3.8 km • 3.1 km • 1.2 km • 1.9 km

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