Answer: Option D is correct.
Explanation: Equation given by de Broglie is:
![\lambda =\frac{h}{mv}](https://tex.z-dn.net/?f=%5Clambda%20%3D%5Cfrac%7Bh%7D%7Bmv%7D)
where,
= wavelength of the particle
h = Planck's constant
m = mass of the particle
v = velocity of the particle
In option A, football will have some mass and is moving with a velocity of 25 m/s, hence it will have some wavelength.
In Option B, unladen swallow also have some mass and is moving with a velocity of 38 km/hr, hence it will also have some wavelength.
In Option C, a person has some mass and is running with a velocity of 7 m/hr, hence it will also have some wavelength.
As, the momentum of these particles are large, therefore the wavelength will be of small magnitude and hence, is not observable.
From the above, it is clearly visible that all the options are having some wavelength, so option D is correct.
Answer:
6. 7870 kg/m³ (3 s.f.)
7. 33.4 g (3 s.f.)
8. 12600 kg/m³ (3 s.f.)
Explanation:
6. The SI unit for density is kg/m³. Thus convert the mass to Kg and volume to m³ first.
1 kg= 1000g
1m³= 1 ×10⁶ cm³
Mass of iron bar
= 64.2g
= 64.2 ÷1000 kg
= 0.0642 kg
Volume of iron bar
= 8.16 cm³
= 8.16 ÷ 10⁶
![= 8.16 \times 10^{ - 6} \: kg](https://tex.z-dn.net/?f=%20%3D%208.16%20%5Ctimes%2010%5E%7B%20-%206%7D%20%5C%3A%20%20kg)
![\boxed{density = \frac{mass}{volume} }](https://tex.z-dn.net/?f=%5Cboxed%7Bdensity%20%3D%20%20%5Cfrac%7Bmass%7D%7Bvolume%7D%20%7D)
Density of iron bar
![= \frac{0.0642}{8.16 \times 10^{ - 6} }](https://tex.z-dn.net/?f=%20%3D%20%20%5Cfrac%7B0.0642%7D%7B8.16%20%5Ctimes%2010%5E%7B%20-%206%7D%20%7D%20)
= 7870 kg/m³ (3 s.f.)
7.
![\boxed{mass = density \: \times volume}](https://tex.z-dn.net/?f=%5Cboxed%7Bmass%20%3D%20density%20%5C%3A%20%20%5Ctimes%20volume%7D)
Mass
= 1.16 ×28.8
= 33.408 g
= 33.4 g (3 s.f.)
8. Volume of brick
= 12 cm³
![= 12 \times 10^{ - 6} \: m^{3} \\ = 1.2 \times 10^{ - 5} \: m ^{3}](https://tex.z-dn.net/?f=%20%3D%2012%20%20%5Ctimes%20%2010%5E%7B%20-%206%7D%20%20%5C%3A%20m%5E%7B3%7D%20%20%5C%5C%20%20%3D%201.2%20%5Ctimes%2010%5E%7B%20-%205%7D%20%20%5C%3A%20m%20%5E%7B3%7D%20)
Mass of brick
= 151 g
= 151 ÷ 1000 kg
= 0.151 kg
Density of brick
= mass ÷ volume
![= \frac{0.151} {1.25 \times 10^{ - 5} } \\ = 12600 \: kg/ {m}^{3}](https://tex.z-dn.net/?f=%20%3D%20%20%5Cfrac%7B0.151%7D%20%7B1.25%20%5Ctimes%2010%5E%7B%20-%205%7D%20%7D%20%20%5C%5C%20%20%3D%2012600%20%5C%3A%20kg%2F%20%7Bm%7D%5E%7B3%7D%20)
(3 s.f.)
Answer: If a substance has a boiling point of
then it is true that it will also change from a gas to a liquid at 78 °C while the gas loses energy.
Explanation:
The temperature at which vapor pressure of a liquid substance becomes equal to the atmospheric pressure is called boiling point of substance.
At the boiling point, liquid phase and vapor phase remains in equilibrium.
This means that as liquid phase changes into vapor phase and also vapor phase changes into liquid phase at the boiling point.
Thus, we can conclude that if a substance has a boiling point of
then it is true that it will also change from a gas to a liquid at 78 °C while the gas loses energy.
Explanation:
Acceleration (a) = 600 m/s²
Mass (m) = 300 kg
Force (F) = ?
We know
F = m * a
= 300 * 600
=180000 Newton
The force acting on the object is 18000 Newton.