Questions: When an object is dropped on a certain earth-like planet, the distance it falls in t seconds, assuming that air resistance is negligible, is given by
s(t) = 19t^2
where s(t) is in feet. Suppose that a medic's reflex hammer is dropped from a hovering helicopter. Find (a) how far the hammer falls in 4 sec, (b) how fast the hammer is traveling 4 sec after being dropped, and (c) the hammer's acceleration after it has been falling for 4 sec.
(a) The hammer falls 304 feet in 4 seconds.
(Simplify your answer.)
(b) The hammer is traveling [] ft/sec 4 seconds after being dropped.
(Simplify your answer.)
Transcript text: When an object is dropped on a certain earth-like planet, the distance it falls in t seconds, assuming that air resistance is negligible, is given by
$s(t) = 19t^2$
where s(t) is in feet. Suppose that a medic's reflex hammer is dropped from a hovering helicopter. Find (a) how far the hammer falls in 4 sec, (b) how fast the hammer is traveling 4 sec after being dropped, and (c) the hammer's acceleration after it has been falling for 4 sec.
(a) The hammer falls 304 feet in 4 seconds.
(Simplify your answer.)
(b) The hammer is traveling [] ft/sec 4 seconds after being dropped.
(Simplify your answer.)
Solution
Solution Steps
Step 1: Calculate the Distance Fallen
To find the distance an object has fallen after 4 seconds, we use the equation $s(t) = k t^2$.
Substituting the given values, $s(4) = 19 \times 4^2 = 304$ units.
Step 2: Calculate the Velocity
The velocity of the object at any time $t$ can be found by differentiating the distance equation with respect to time.
This gives $v(t) = 2kt = 2 \times 19 \times 4 = 152$ units per second.
Step 3: Calculate the Acceleration
The acceleration of the object is constant and can be found by differentiating the velocity equation with respect to time or directly from the knowledge that $a = 2k$.
Thus, the acceleration due to gravity on this planet is $a = 2 \times 19 = 38$ units per square second.
Final Answer:
The distance fallen after 4 seconds is 304 units, the velocity at 4 seconds is 152 units per second, and the constant acceleration due to gravity is 38 units per square second.