Physics Unit 3

A cannonball is launched from the ground at an angle of 30 degrees and at a speed of 20 m/s. Ideally (no air resistance) the ball will land on the ground with a vertical velocity of a) 40 m/s b) 20 m/s c) 10 m/s d) 0 m/s e) there is not enough information to say

30 degrees is at x axis, to get to y axis you do 20sin30. since sin 30 is 1/2, you get 10 m/s

In the absence of air resistance, the angle at which a thrown ball will go the farthest is a) 75 degrees b) 60 degrees c) 45 degrees d) 30 degrees e) 15 degrees

C) 45 degrees

A ball thrown in the air will never go as far as physics ideally would predict because a) one can never throw the ball fast enough b) gravity is acting c) ideally the ball would never land d) air friction slows the ball e) all of the above

D) all friction slows the ball

A cannonball is fired at some angle into the air. In the first second it moves 10 meters horizontally. Assuming it doesn't hit the ground and air resistance is small, how far does it move horizontally in the next second? a) more than 10 m b) 10 m c) less than 10 m d) theres not enough information to say

B) 10 m

Two spheres A&B are projected off the edge of a 2.0m high table with the same horizontal velocity. Sphere A has a mass of 10 g and Sphere B has a mass of 5 g. If both spheres leave the edge of the table at the same instant, sphere A hits the floor at the spot marked X. Sphere B will hit the floor a) at some point between the edge of the table and X b) at the same distance from the table as X c) at some point past X d) Theres not enough information to decide

B) at the same distance from the table as X

A ball is thrown into the air at some angle. At the very top of the ball's path, its velocity is a) entirely vertical b) entirely horizontal c) both vertical and horizontal d) theres not enough information given to determine

B) entirely horizontal

In the absence of air friction, the horizontal component of a projectile's velocity doesn't change as the projectile moves. a) Always True b) Sometimes True c) Always False

a) Always true

Two spheres a and b, where A has twice the mass of B, are projected at the same horizontal velocity off the edge of two different height shelves. Sphere A leaves from a height of 2 m. Sphere B leaves from a shelf of 1.0m off the floor. If both spheres leave the edge of the table at the same instant, sphere A hits the floor at the spot marked X. Sphere B will hit the floor a) at some point between the edge of the table and x b) at the same distance from the table as x c) At some point past X d) there is not enough information to decide

a) at some point between the edge of the table and x

The horizontal component of a projectile's velocity is independent of a) the vertical component of its velocity b) the range of the projectile c) time

a) the vertical component of its velocity

An object is dropped and falls freely to the ground with an acceleration of 1g. If it is thrown upward at an angle instead, its acceleration would be a) 0 g b) 1 g downward c) 1 g upward d) larger than 1 g e) none of the above

b) 1 g downward

Two spheres a and b, where A has twice the mass of B, are projected at the same horizontal velocity off the edge of two different height shelves. Sphere A leaves from a height of 2 m. Sphere B leaves from a shelf of 1.0m off the floor. If both spheres leave the edge of the table at the same instant,sphere A will land a) at some time before sphere b b) at some time after sphere b c) at the same time as sphere b d) there's not enough info to decide

b) at some time after sphere b

A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component of speed because it a) is not acted on by any forces b) is not acted on by any horizontal forces c) has no vertical component of speed to begin with d) the net force acting on it is zero e) None of the above

b) is not acted on by any horizontal forces

A bullet fired horizontally hits the ground in 0.5 s. If it had been fired with a much higher speed in the same direction, it would have hit the ground (neglecting the earth's curvature and air resistance) in a) less than .5 seconds b) more than .5 seconds c) .5 seconds

c) .5 seconds

A rifle with a firing velocity of 100 m/s is fired horizontally from a tower. Neglecting air resistance, where will the bullet be 1 second later? a) 50 m downrange b) 98 m downrange c) 100 m downrange d) 490 m downrange e) None of the above

c) 100 m downrange

In the absence of air friction, the vertical component of a projectile's velocity doesn't changes as the projectile moves. a) Always True b) Sometimes True c) Always False

c) Always False

Two spheres A&B are projected off the edge of a 2.0m high table with the same horizontal velocity. Sphere A has a mass of 10 g and Sphere B has a mass of 5 g. If both spheres leave the edge of the table at the same instant, Sphere A will land a) at some time before sphere B b) at some time after sphere B c) at the time as sphere B d) there is not enough information to decide

c) at the same time as sphere b

At what part of a path does a projectile have minimum speed? a) when it is thrown b) half way to he top c) at the top of its path d) when it returns to the ground e) theres not enough information to say

c) at the top of its path

If a freely falling object were somehow equipped with an odometer to measure the distance it travels, then the distance it travels each succeeding second would be a) the same b) less than the previous second c) greater than the previous second d) the distance cannot be predicted

c) greater than the previous second

At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Whit ball hits the ground first? a) the horizontally thrown ball b) the dropped ball c) neither--they both hit the ground at the same time

c) neither they both ground at the same time

After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance) a) greater than when it was at the top of its path b) less than when it was at the top of its path c) the same as when it was at the top of its path

c) the same as when it was at the top of its path

A ball is hurled into the air at an angle of 30 degrees and lands on a target that is at the same level as that where the ball started. The ball will also land on the target that is thrown at an angle of a) 40 degrees b) 45 degrees c) 55 degrees d) 60 degrees e) none of the above

d) 60 degrees