Answer:
Angular acceleration, is 
Explanation:
Given that,
Initial speed of the drill, 
After 4.28 s of constant angular acceleration it turns at a rate of 28940 rev/min, final angular speed, 
We need to find the drill’s angular acceleration. It is given by the rate of change of angular velocity.

So, the drill's angular acceleration is
.
Answer:
h = 5.05 m
Explanation:
given,
mass of pole vaulter, m = 64 Kg
speed of the vaulter,V = 10.2 m/s
horizontal component of velocity in air, v = 1 m/s
height of the jump,h = ?
using energy conservation


initial height of the vaulter is equal to zero.



h = 5.05 m
height of the jump is equal to 5.05 m.
Answer:
.25 Hz
Explanation:
Period = 4 sec
freq = 1/p = 1/4 hz = .25 Hz
<span>There are approximately 1600 meters/mile. Estimating a five second per mile delay in the arrival of the sound, then the estimate of the speed of sound is (a)1600/5 or 320 meters/sec or (B) 320 x 60 sec x 60 min / 1600 m/mile or about 720 miles/hour.</span>