physics chapter 4

Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30°. When the snowballs reach the ground below, A) Debra's snowball will stay in the air longer than Mary's. B) Mary's snowball will stay in the air longer than Debra's. C) Both snowballs will take the same amount of time to hit the ground. D) Debra's snowball never hits the ground since it is thrown upwards. E) Mary's snowball never hits the ground since it is thrown downwards.

A) Debra's snowball will stay in the air longer than Mary's.

For which value of θ is the range of a projectile fired from ground level a maximum? A) 30° above the horizontal B) 45° above the horizontal C) 55° above the horizontal D) 60° above the horizontal E) 90° above the horizontal

B) 45° above the horizontal

Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30°. When the snowballs reach the ground below, A) Debra's snowball will have a higher speed than Mary's. B) Mary's snowball will have a higher speed than Debra's. C) Both snowballs will hit the ground with the same speed. D) Debra's snowball never hits the ground since it is thrown upwards. E) Mary's snowball never hits the ground since it is thrown downwards.

C) Both snowballs will hit the ground with the same speed.

A rock is thrown from ground level at some angle above the horizontal with a certain velocity. It reaches its highest point and starts falling down. What is the magnitude of the velocity of the rock right before it hits the ground? A) It is equal to its initial vertical velocity. B) It is equal to its initial horizontal velocity. C) It is equal to the magnitude of its initial velocity. D) 0 E) Cannot be determined without additional information.

C) It is equal to the magnitude of its initial velocity

Marcia uses a bow to shoot an arrow with initial velocity of magnitude v0 and at an angle θ above the horizontal. When the arrow returns to the same height from which it started, A) the speed of the arrow is twice v0. B) the speed of the arrow is 9.8 times larger than v0. C) the speed of the arrow is again v0. D) the speed of the arrow is sqrt 2* v0. E) the speed of the arrow is v0/.sqrt 2

C) the speed of the arrow is again v0.

A ball is thrown with a velocity of 40 m/s at an angle of 30° above the horizontal and attains a certain range R. At what other angle will this ball attain the same range keeping its initial velocity the same? A) 15° B) 90° C) 120° D) 60° E) All other angles will give different ranges.

D) 60°

If the initial speed of a projectile is doubled. A) Its range will be increased by 1.41. B) Its range will double. C) Its range will be decreased by a factor of two. D) Its range will quadruple. E) Its range will decrease by a factor of four.

D) Its range will quadruple.

A projectile is launched with initial velocity v0 at an angle of 30° above the horizontal. If a second projectile is launched with the same initial velocity but at angle of 60° above the horizontal. A) The range of the second projectile will be twice that of the first. B) The range of the second projectile will be 1.41 that of the first. C) The range of the second projectile will be one-half that of the first. D) The ranges of the two projectiles will be identical. E) It is impossible to compare the ranges of the two projectiles.

D) The ranges of the two projectiles will be identical.

For which value of θ is the height of a projectile fired from ground level a maximum? A) 30° above the horizontal B) 45° above the horizontal C) 55° above the horizontal D) 60° above the horizontal E) 90° above the horizontal

E) 90° above the horizontal