Physics Lecture 5

A cat leaps to catch a bird. If the cat's jump was at 60.0° off the ground and its initial velocity was 2.74 m/s, what is the highest point of its trajectory? A) 0.19 m B) 0.58 m C) 10.96 m D) 0.29 m

D

A football kicker is attempting a field goal from 44 m out. The ball is kicked and just clears the lower bar with a time of flight of 2.9 s. If the angle of the kick was 45°, what was the initial speed of the ball? A) 21.5 m/s B) 19.7 m/s C) 2.2 m/s D) 39 m/s

A

A hobby rocket reaches a height of 72.3 m and lands 111 m from the launch point. What was the angle of launch? A) 69.0° B) 67.4° C) 22.6° D) -44.8°

A

A projectile is fired at time t = 0.0 s, from point 0 at the edge of a cliff, with initial velocity components of vox = 50 m/s and voy =200 m/s. The projectile rises, then falls into the sea at point P. The time of flight of the projectile is 50.0 s. In the figure, the y-coordinate of the projectile when its x-coordinate is 1000 m is closest to: A) +2040 m B) 150 m C) -150 m D) +1240 m E) + 600 m

A

Jeff ran up the hill at 7.0 m/s. The horizontal component of Jeff's velocity vector was 5.1 m/s. What was the vertical component of Jeff's velocity? A) 4.8 m/s B) 4.3 m/s C) 3.8 m/s D) 3.4 m/s

A

What is the maximum distance we can shoot a dart, provided our toy dart gun gives a maximum initial velocity of 2.78 m/s? A) 0.79 m B) 1.58 m C) 1.39 m D) More information needed

A

A boat crosses a river at a constant engine speed of 8.0 cm/s under the influence of a constant perpendicular current acceleration of 0.060 m/s2. How far off a straight course does it drift in 2.3 min? A) 0.16 m B) 570 m C) 4.1 m D) 1700 m

B

A projectile is fired at time t = 0.0 s, from point 0 at the edge of a cliff, with initial velocity components of vox = 30 m/s and voy =300 m/s. The projectile rises, then falls into the sea at point P. The time of flight of the projectile is 75.0 s. In the figure, the horizontal distance D is closest to: A) 2520 m B) 2250 m C) 2790 m D) 3060 m E) 3330 m

B

A boy throws a rock with an initial velocity of 3.13 m/s at 30.0° above the horizontal. How long does it take for the rock to reach the maximum height of its trajectory? A) 0.313 s B) 0.282 s C) 0.160 s D) 0.441 s

C

A fisherman casts his bait into the river at an angle of 25°. As the line unravels, he notices that the bait and hook reach a maximum height of 3.9 m. What was the initial velocity he launched the bait with? A) 10 m/s B) 9.2 m/s C) 21 m/s D) 8.4 m/s

C

A glider is tugged by an airplane at 81 m/s when it is released. If the original speed was along the horizontal and the glider is now under a constant acceleration of 2.4 m/s2 at 1.1° below the horizontal due to air drag, how long will it take to reach the ground 5.7 km below? A) 2.2 s B) 250,000 s C) 500 s D) 4.8 s

C

Jordan ran up the hill at 7.0 m/s. The horizontal component of Jordan's velocity vector was 1.8 m/s. What was the angle of the hill? A) 33 degrees B) 57 degrees C) 75 degrees D) 15 degrees

C

A projectile is fired from the origin (at y = 0 m) as shown in the figure. The initial velocity components are vox = 940 m/s and voy = 96 m/s. The projectile reaches maximum height at point P, then it falls and strikes the ground at point Q. In the figure, the y-coordinate of point P is closest to: A) 940 m B) 45,550 m C) 45,080 m D) 470 m E) 90,160 m

D

A football is kicked toward the goal posts and feels no air resistance. While it is in the air, the only force acting on it is 9.8 m/s2 downward due to gravity.

F

A grasshopper leaps into the air at a 62 degree angle above the horizontal. At its highest point, the grasshopper's velocity and acceleration are equal to zero.

F

You can launch a projectile with a fixed initial speed but at any angle above the horizontal, and it feels no air resistance. The time for it to return to the ground does not depend on the angle at which you launch it.

F

A ball is thrown at an angle above the horizontal from the top of a cliff and feels no air resistance. A runner at the base of the cliff moves horizontally so that she is always under the ball. In this runner's reference frame, the path of the ball is a straight line rather than a parabola.

T

You throw a 5.0 kg stone from the top of a cliff with an initial vertical velocity of 8.0 m/s downward and an initial horizontal velocity of 7.0 m/s away from the cliff, and it feels no air resistance. After the stone is in the air but free of your hand, its acceleration remains constant at 9.8 m/s2 downward but its speed changes.

T