Unit 3 projectiles
A hunter aims directly at a target (on the same level) 75.0 m away. (a) If the bullet leaves the gun at a speed of 180 m/s, by how much will it miss the target?
(a) 0.851 m (b) 0.650°
A projectile is shot horizontally at 23.4 m/s from the roof of a building 55.0 m tall. (a) Determine the time necessary for the projectile to reach the ground below. (b) Determine the distance from the base of the building that the projectile lands. (c) Determine the horizontal and vertical components of the velocity just before the projectile reaches the ground.
(a) 3.35 s (b) 78.4 m (c) vhorizontal = 23.4 m/s, vvertical = 32.8 m/s
foul ball is hit straight up into the air with a speed of 30.0 m/s. (a.) Calculate the time required for the ball to rise to its maximum height. (b.) Calculate the maximum height reached by the ball. (c.) Determine the time at which the ball pass a point 25.0 m above the point of contact between the bat and ball. (d.) Explain why there are two answers to part c.
(a.) 3.06 s (b.) 45.9 m (c.) 0.995 s and 5.13 s (d.) One value for the ball traveling upward; one value for the ball traveling downward.
An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration in meters per second per second is approximately
0
Starting from rest, the distance a freely falling object will fall in 0.5 s is about
1.25 m
An apple falls from a tree and hits the ground 5 m below. It hits the ground with a speed of about
10 m/s
Disregarding air drag, how fast must you toss a ball straight up in order for it to take 2 seconds to return to the level from which you tossed it?
10 m/s
Disregarding air drag, how fast must you toss a ball straight up in order for it to take 2 seconds to return to the level from which you tossed it?
10 m/s
If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by about
10 m/s
An object falls freely from rest on a planet where the acceleration due to gravity is 20 meters per second squared. After 5 seconds, the object will have a speed of
100 m/s
An object falls freely from rest on a planet where the acceleration due to gravity is twice as much as it is on Earth. In the first 5 seconds it falls a distance of
250 m
One-half second after starting from rest, a freely falling object will have a speed of about
5 m/s
If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is
6 km/h/s
An object is in free fall. At one instant, it travels at a speed of 50 m/s. Exactly 1 s later, its speed is about
60 m/s
A ball thrown horizontally from a point 24 m above the ground, strikes the ground after traveling horizontally a distance of 18 m. With what speed was it thrown?
8.1 m/s
A stone is thrown horizontally at 10 m/s from the edge of a cliff. A stop watch measures the stone's trajectory time from the top of the cliff to the bottom to be 4.3 s. What is the height of the cliff?
91 m
It takes 6 s for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
About 180 m
A bullet is fired horizontally, and at the same instant a second bullet is dropped from the same height. Ignore air resistance. Compare the times of fall of the two bullets.
They hit at the same time
The vertical height attained by a basketball player who achieves a hang time of a full 1 s is
about 1.2 m
Disregarding air resistance, objects fall at constant
acceleration
If an object moves with constant acceleration, its velocity must
change by the same amount each second
If a freely falling object were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before
If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before
In each second of fall, the distance a freely falling object will fall is
increasing
A bullet is fired straight down from the top of a high cliff. Neglecting air resistance, the acceleration of the bullet in meters per second per second
is 9.8
A ball is thrown upward and caught when it comes back down. In the presence of air resistance, the speed with which it is caught is
less than the speed it had when thrown upward
A ball is thrown upwards and caught when it comes back down. In the presence of air resistance, the speed with which it is caught is always
less than the speed it had when thrown upwards
Someone standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, the ball to hit the ground below the cliff with the greater speed will be
neither -- they will both hit with the same speed
Ignoring air resistance, the horizontal component of a projectile's velocity
remains constant
When a rock thrown straight upwards gets to the exact top of its path, its
velocity is zero and its acceleration is about 10 meters per second per second.
