Answer:
450 kJ
Explanation:
Q = mCΔT
where Q is heat (energy),
m is mass,
C is specific heat capacity,
and ΔT is the temperature change.
Q = (1.2 kg) (4180 J/kg/°C) (100°C − 10°C)
Q = 451,440 J
Q ≈ 450 kJ
Answer:
True.
Explanation:
According to Lenz's law, the induced current in a circuit always flows to oppose the external magnetic field through the circuit. This statement is true.
The Faraday's law of induction is given by :
Here, negative sign shows that the direction of induced emf is such that opposes the changing current that is its cause.
Hence, the statement is true.
(3 m) / (2 mm/yr) = (3,000mm)/(2mm/yr) = 1,500 yrs.
This is the time required to age approx 75 generations of the best wine.
Answer:Bruce is knocked backwards at
14
m
s
.
Explanation:
This is a problem of momentum (
→
p
) conservation, where
→
p
=
m
→
v
and because momentum is always conserved, in a collision:
→
p
f
=
→
p
i
We are given that
m
1
=
45
k
g
,
v
1
=
2
m
s
,
m
2
=
90
k
g
, and
v
2
=
7
m
s
The momentum of Bruce (
m
1
) before the collision is given by
→
p
1
=
m
1
v
1
→
p
1
=
(
45
k
g
)
(
2
m
s
)
→
p
1
=
90
k
g
m
s
Similarly, the momentum of Biff (
m
2
) before the collision is given by
→
p
2
=
(
90
k
g
)
(
7
m
s
)
=
630
k
g
m
s
The total linear momentum before the collision is the sum of the momentums of each of the football players.
→
P
=
→
p
t
o
t
=
∑
→
p
→
P
i
=
→
p
1
+
→
p
2
→
P
i
=
90
k
g
m
s
+
630
k
g
m
s
=
720
k
g
m
s
Because momentum is conserved, we know that given a momentum of
720
k
g
m
s
before the collision, the momentum after the collision will also be
720
k
g
m
s
. We are given the final velocity of Biff (
v
2
=
1
m
s
) and asked to find the final velocity of Bruce.
→
P
f
=
→
p
1
f
+
→
p
2
f
→
P
f
=
m
1
v
1
f
+
m
2
v
2
f
Solve for
v
1
:
v
1
f
=
→
P
f
−
m
2
v
2
f
m
1
Using our known values:
v
1
f
=
720
k
g
m
s
−
(
90
k
g
)
(
1
m
s
)
45
k
g
v
1
f
=
14
m
s
∴
Bruce is knocked backwards at
14
m
s
.
Explanation:
Answer:
Explanation:
For fundamental frequency in a vibrating string , the formula is
n = 1 / 2L x √ ( T /m₁ )
n is frequency , L is length , T is tension and m₁ is mass per unit length .
For first string ,
293 = 1 / 2L x √ ( 49 N /m₁ )
For second string , let mass per unit length be m₂ .
196 = 1 / 2L x √ ( 49 N /m₂ ) ------ ( 1 )
To bring its frequency back to previous one let tension be T
293 = 1 / 2L x √ ( T /m₂ ) ------- ( 2 )
Dividing
293 / 196 = √ ( T /49 )
1.4948 = √ ( T /49 )
2.2344 = T /49
T = 109.48 N .
