Answer:
Al's mass is 102.92 kg
Explanation:
As there are no external forces in the horizontal direction, the horizontal net force must be zero:
As the force is the derivative in time of the momentum, this means that the horizontal momentum is constant:
where the suffix i and f means initial and final respectively.
The initial momentum will be:
But, as they are at rest, initially
So, this means:
We know that the have an combined mass of 195 kg:
.
so:
.
Now, we can use the values:
where the minus sign appears as they are moving at opposite directions
and this is the Al's mass.
Answer: C. Meyer did not leave gaps while Mendeleev did.
Explanation: Mendeleev's table was table different from Meyer's table because Meyer did not leave gaps while Mendeleev did.
Answer:
Incorrect statement is (b).
Explanation:
Option (a) : There is an inverse relation between the time and the frequency. The time taken depends on the frequency of the number of oscillations. Statement 1 is correct i.e. the time taken by any point of the wave to make one complete oscillation does not depend on the amplitude.
Option (b) : Speed of a wave is given by the product of its frequency and wavelength. It is not necessary that doubling the wavelength of the wave will halve its frequency as speed depends on the medium.
Option (c) : Doubling the amplitude has no effect on on the wavelength as amplitude does not depends on its wavelength.
Option (d) : Since,
Speed is directly proportional to the frequency and wavelength. So, doubling the frequency of the wave will double its speed. So, the incorrect statement is (b).
The work done is the same as the amount of energy increase. The formula for kinetic energy is 122
1
2
m
v
2
.
The initial KE of the car is 12(1000)×202=200,000
1
2
(
1000
)
×
20
2
=
200
,
000
joules.
The final KE of the car is 12(1000)×302=450,000
1
2
(
1000
)
×
30
2
=
450
,
000
joules.
The difference between these is the amount of work done: 450,000−200,000=250,000
450
,
000
−
200
,
000
=
250
,
000
joules.
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