Since there isn't a word about the direction of the taxi's
motion, we're in no position to talk about 'velocity', so we'll
just talk about 'speed'.
|Acceleration| = (change in speed) / (time for the change)
= (230 mph) / (30 sec)
= 23/3 mile / hour-sec .
This is just a hypothetical question, made up for Physics practice ...
so I'm not too worried about the taxi's final speed of 230 mph.
There's no way the Police are going to catch him, even in their
helicopter, so he's safe for a while.
What DOES bother me is that ugly unit for acceleration ...
mile / hour-second. It's a perfectly valid unit of acceleration,
having the dimensions of [distance / time²], but it's not one
that anybody has a feeling for, so we can't relate to it and we
don't know what it means. We need to change it to a unit that
we understand. That's not hard to do.
(230 mile/hour-sec) x (1,609 meter/mile) x (1 hour/3,600 seconds)
= (230 x 1,609 / 3,600) meters/second²
= 102.82 m/s² = 10.5 G's !
That's a problem. The taxi is pulling 10.5 G's, the police helicopter
is in hot pursuit, the driver is passing out, and the taxi is almost
certainly falling apart around him. Meanwhile, from the back seat,
the passenger is yelling "Check your data!". CHECK YOUR DATA !
I = 4 A
Explanation:
From Ohm's law, the voltage is given by
V = IR
or
I = V/R = (80 V)/(20 ohms)
= 4 A
Answer:
r = 20 m
Explanation:
The formula for the angular momentum of a rotating body is given as:
L = mvr
where,
L = Angular Momentum = 10000 kgm²/s
m = mass
v = speed = 2 m/s
r = radius of merry-go-round
Therefore,
10000 kg.m²/s = mr(2 m/s)
m r = (10000 kg.m²/s)/(2 m/s)
m r = 5000 kg.m ------------- equation 1
Now, the moment of inertia of a solid uniform disc about its axis through its center is given as:
I = (1/2) m r²
where,
I = moment of inertia = 50000 kg.m²
Therefore,
50000 kg.m² = (1/2)(m r)(r)
using equation 1, we get:
50000 kg.m² = (1/2)(5000 kg.m)(r)
(50000 kg.m²)/(2500 kg.m) = r
<u>r = 20 m</u>