Question

Charlie the cat climbs a mountain. She goes to the edge and throws Rosie’s bone off the mountain with a speed of 2 m/s. If the final speed of the bone is 45 m/s, how many seconds did the bone fall?

a) 21.5 seconds
b) 20.5 seconds
c) 22.5 seconds
d) 23.5 seconds

Answer 1

To find out how many seconds the bone fell, we use the kinematic equation v = u + at, solving for time (t), given the initial and final speeds and the acceleration due to gravity. The correct calculation shows that the bone fell for approximately 4.39 seconds.

Step-by-step explanation:

Charlie the cat throws Rosie's bone off the mountain with an initial speed of 2 m/s and it reaches a final speed of 45 m/s. To find out how many seconds the bone fell, we can use the kinematic equation for uniformly accelerated motion, assuming the acceleration due to gravity (g) is 9.8 m/s2:

v = u + at

Where:
v = final velocity (45 m/s)
u = initial velocity (2 m/s)
a = acceleration (g = 9.8 m/s2)
t = time (in seconds)

Solving for t, we rearrange the equation to:

t = (v - u) / a

Substituting the values:

t = (45 m/s - 2 m/s) / 9.8 m/s2

t = 43 m/s / 9.8 m/s2

t ≈ 4.39 seconds

Therefore, B) 4.39 seconds is the correct answer.