The position vector of an object of mass 0.5 kg is given by r 2.0t2i+ 3.0tj m where t represents time. Which ONE of the followin
1 answer:
Answer:
Statement E is false.
Explanation:
Statement a says that the object would have moved a distance of 10 m.
At t = 0
x0 = 0
y0 = 0
At t= 2
x2 = 2 * 2^2 = 8
y2 = 3 * 2 = 6
Statement A is true.
Statement B says that the momentum of the object would be 4*i+1.5*j
To test this we need to know the speed.
The speed is the first derivative by time:
v = 4*t*i + 3*j
At t = 2 the speed is
v2 = 8*i + 3*j
The momentum is
P = m * v
P2 = 0.5 * (8*i + 3*j) = (4*i+1.5*j)
This statement is true.
Statement C says that the kinetic energy of the object would be 18 J.
The magnitude of the speed is
The kinetic energy is
Ek = 1/2 * m * v^2
Ek = 1/2 * 0.5 * 8.54^2 = 18 J
Statement C is true
Statement D says that the force acts perpenducular to the direction of the unit vector j.
The acceleration is the second derivative respect of time
a = 4*i + 0*j
Since there is no acceleration in the direction of j we can conclude that the force is perpendicular to the direction of j.
Statement D is true.
Statement E says that the force acting on the object is of 4 N
f = m * a
f = 0.5 * 4 = 2 N
Statement E is false.
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Answer:
Wavelength = 736.67 nm
Explanation:
Given
Energy of the photon = 2.70 × 10⁻¹⁹ J
Considering:
where, h is Plank's constant having value as 6.63 x 10⁻³⁴ J.s
The relation between frequency and wavelength is shown below as:
c = frequency × Wavelength
Where, c is the speed of light having value = 3×10⁸ m/s
So, Frequency is:
Frequency = c / Wavelength
So, Formula for energy:
Energy = 2.70 × 10⁻¹⁹ J
c = 3×10⁸ m/s
h = 6.63 x 10⁻³⁴ J.s
Thus, applying in the formula:
Wavelength = 736.67 × 10⁻⁹ m
1 nm = 10⁻⁹ m
So,
<u>Wavelength = 736.67 nm</u>
Compared to the pucks given, the pair of pucks will rotate at the same rate.
Answer: Option A
<u>Explanation:</u>
The law of conservation of the angular momentum expresses that when no outer torque follows upon an article, no difference in angular momentum will happen. At the point when an item is turning in a shut framework and no outside torques are applied to it, it will have no change in angular momentum.
The conservation of the angular momentum clarifies the angular quickening of an ice skater as she brings her arms and legs near the vertical rotate of revolution. In the event, that the net torque is zero, at that point angular momentum is steady or saved.
By twice the mass yet keeping the speeds unaltered, also twice the angular momentum's to the two-puck framework. Be that as it may, we likewise double the moment of inertia. Since , the turning rate of the two-puck framework must stay unaltered.