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Answer: The mass of ball is 10 grams.
Explanation:
Given : Kinetic energy = 4.5 J
Velocity = 30 m/s
The formula for Kinetic energy is as follows.
where,
K.E = Kinetic energy
m = mass
v = velocity
Substitute the values into above formula as follows.
Thus, we can conclude that the mass of ball is 10 grams.
Answer:
The speed of the rod is 2.169 m/s.
Explanation:
Given that,
Mass = 0.100 kg
Current = 15.0 A
Distance = 2 m
Length = 0.550 m
Kinetic friction = 0.120
(a). We need to calculate the magnetic field
Using relation of frictional force and magnetic force
Where, l = length
i = current
m = mass
Put the value into the formula
(b). If the friction between the rod and rail is reduced zero.
So,
We need to calculate the acceleration
Using formula of force
Put the value into the formula
We need to calculate the speed of the rod
Using equation of motion
Put the value into the formula
Hence, The speed of the rod is 2.169 m/s.
The resistance is 4 times the resistance of the first wire. the formula is R = p*l/A with p being resistivity, l length and A area. So if you double length and half area, which botv result in more resistance, you get p*2/0.5 or 4 (p can be abandoned because it is the same. We take standard length and area as 1)