A 5 kg block moves with a constant speed of 10 ms to the right on a smooth surface where frictional forces are considered to be
2 answers:
Answer:
Work done, W = 19.6 J
Explanation:
It is given that,
Mass of the block, m = 5 kg
Speed of the block, v = 10 m/s
The coefficient of kinetic friction between the block and the rough section is 0.2
Distance covered by the block, d = 2 m
As the block passes through the rough part, some of the energy gets lost and this energy is equal to the work done by the kinetic energy.
W = 19.6 J
So, the change in the kinetic energy of the block as it passes through the rough section is 19.6 J. Hence, this is the required solution.
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First, let's find the speed 
of the two blocks m1 and m2 sticked together after the collision.
We can use the conservation of momentum to solve this part. Initially, block 2 is stationary, so only block 1 has momentum different from zero, and it is:
After the collision, the two blocks stick together and so now they have mass
and they are moving with speed :
For conservation of momentum
So we can write
From which we find
The two blocks enter the rough path with this velocity, then they are decelerated because of the frictional force
. The work done by the frictional force to stop the two blocks is
where d is the distance covered by the two blocks before stopping.
The initial kinetic energy of the two blocks together, just before entering the rough path, is
When the two blocks stop, all this kinetic energy is lost, because their velocity becomes zero; for the work-energy theorem, the loss in kinetic energy must be equal to the work done by the frictional force:
From which we can find the value of the coefficient of kinetic friction:
We can use the conservation of momentum to solve this part. Initially, block 2 is stationary, so only block 1 has momentum different from zero, and it is:
After the collision, the two blocks stick together and so now they have mass
For conservation of momentum
So we can write
From which we find
The two blocks enter the rough path with this velocity, then they are decelerated because of the frictional force
where d is the distance covered by the two blocks before stopping.
The initial kinetic energy of the two blocks together, just before entering the rough path, is
When the two blocks stop, all this kinetic energy is lost, because their velocity becomes zero; for the work-energy theorem, the loss in kinetic energy must be equal to the work done by the frictional force:
From which we can find the value of the coefficient of kinetic friction:
Answer:
(a) momentum of photon is 1.205 x 10⁻²⁷ kgm/s
velocity of electron is 1323.88 m/s
momentum of the electron is 1.205 x 10⁻²⁷ kgm/s
(b) momentum of photon is 1.506 x 10⁻²⁷ kgm/s
velocity of electron is 1654.85 m/s
momentum of the electron is 1.506 x 10⁻²⁷ kgm/s
(c) The momentum of the photon is equal to the momentum of the electron
Explanation:
(a)
wavelength of green light, λ = 550 nm
momentum of photon is given by;
velocity of electron is given by;
momentum of the electron is given by;
p = mv
p = (9.1 x 10⁻³¹) (1323.88)
p = 1.205 x 10⁻²⁷ kgm/s
(b)
wavelength of red light, λ = 440 nm
momentum of photon is given by;
velocity of electron is given by;
momentum of the electron is given by;
p = mv
p = (9.1 x 10⁻³¹) (1654.85)
p = 1.506 x 10⁻²⁷ kgm/s
(c) The momentum of the photon is equal to the momentum of the electron.
Answer:
22.7 meters
Explanation:
Let's remind the difference between distance and displacement:
- distance: the total distance travelled by an object in all its paths
- displacement: the different between the final and initial position of the object
In this case, the problem asks to find the distance covered by the ball. This will be the sum of the distances covered by the ball in each part of its motion, therefore:
(instead, the displacement will be the difference between the final and initial position of the ball, therefore:
)