I'd go with electricity source. Good luck!!
I believe the answer is b) slowly heating the surface
Answer:
33.2 m
Explanation:
For the first object:
y₀ = 81.5 m
v₀ = 0 m/s
a = -9.8 m/s²
t₀ = 0 s
y = y₀ + v₀ t + ½ at²
y = 81.5 − 4.9t²
For the second object:
y₀ = 0 m
v₀ = 40.0 m/s
a = -9.8 m/s²
t₀ = 2.20 s
y = y₀ + v₀ t + ½ at²
y = 40(t−2.2) − 4.9(t−2.2)²
When they meet:
81.5 − 4.9t² = 40(t−2.2) − 4.9(t−2.2)²
81.5 − 4.9t² = 40t − 88 − 4.9 (t² − 4.4t + 4.84)
81.5 − 4.9t² = 40t − 88 − 4.9t² + 21.56t − 23.716
81.5 = 61.56t − 111.716
193.216 = 61.56t
t = 3.139
The position at that time is:
y = 81.5 − 4.9(3.139)²
y = 33.2
Answer:
2653 turns
Explanation:
We are given that
Diameter,d=2 cm
Length of magnet,l=8 cm=
1m=100 cm
Magnetic field,B=0.1 T
Current,I=2.4 A
We are given that
Magnetic field of solenoid and magnetic are same and size of both solenoid and magnetic are also same.
Length of solenoid=
Magnetic field of solenoid

Using the formula

Where 
