Explanation:
The given data is as follows.
k = 130 N/m,
= 17 cm = 0.17 m (as 1 m = 100 cm)
mass (m) = 2.8 kg
When the spring is compressed then energy stored in it is as follows.
Energy = 
Now, spring energy gets converted into kinetic energy when the box is launched.
So,
= 
= 

= 1.34
v = 1.15 m/sec
Now,
Frictional force = 
= 
= 4.116 N
Also, Kinetic energy = work done by friction
1.8515 =
d = 0.449 m
Thus, we can conclude that the box slides 0.449 m across the rough surface before stopping.
Answer:
(a) The current should be in opposite direction
(b) The current needed is 39.8 A
Explanation:
Part (a)
Based, on right hand rule, the current should be in opposite direction
Part (b)
given;
strength of magnetic field, B = 370 µT
distance between the two parallel wires, d = 8.6 cm

At the center, the magnetic field strength is twice

R = d/2 = 8.6/2 = 4.3 cm = 0.043 m

Therefore, current needed is 39.8 A
Answer:
The maximum amount of meat that the butcher can sell is 
Explanation:
The maximum amount can be found by taking the difference of mixed numbers.

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