the answer is a because they start on the north side
Answer:
59.4 meters
Explanation:
The correct question statement is :
A floor polisher has a rotating disk that has a 15-cm radius. The disk rotates at a constant angular velocity of 1.4 rev/s and is covered with a soft material that does the polishing. An operator holds the polisher in one place for 4.5 s, in order to buff an especially scuff ed area of the floor. How far (in meters) does a spot on the outer edge of the disk move during this time?
Solution:
We know for a circle of radius r and θ angle by an arc of length S at the center,
S=rθ
This gives
θ=S/r
also we know angular velocity
ω=θ/t where t is time
or
θ=ωt
and we know
1 revolution =2π radians
From this we have
angular velocity ω = 1.4 revolutions per sec = 1.4×2π radians /sec = 1.4×3.14×2×= 8.8 radians / sec
Putting values of ω and time t in
θ=ωt
we have
θ= 8.8 rad / sec × 4.5 sec
θ= 396 radians
We are given radius r = 15 cm = 15 ×0.01 m=0.15 m (because 1 m= 100 cm and hence, 1 cm = 0.01 m)
put this value of θ and r in
S=rθ
we have
S= 396 radians ×0.15 m=59.4 m
Answer:
See below
Explanation:
You have to heat the calorimeter to 100 C from 20 C
this will take .20 kg * 390 j /kg-C * 80 C = <u>6240 j</u>
You have to heat the mass of water to boiling point (100 C ) from 20C
this will take
.50 kg * 4182 j/kg-C * 80 = <u>167,280 j </u>
AND you have to add enough heat to boil off .03 kg of water:
.03 kg * (2260000 j/kg-C ) =<u> 67,800 j</u>
<u />
Power = joules / sec = (6240 + 167280 + 67800) / 274.8 =<u> 878 watts </u>
<u />
<u>Your answer may differ just a bit for slightly different or rounded values of specific heat or heat of fusion for water .....</u>
Answer:
6s
Explanation:
Assume it is dropped from rest and the gravitational acceleration is 10
By the equation of motion under constant acceleration:
180 = (0)t+10(t^2)/2
t = 6 or -6 (rejected)
t = 6 s
