Answer: When enough __energy__ is added to the substance, the solid reaches its _melting_ point and becomes a liquid
Explanation: since energy is being added the substance changes phase into a liquid .
Answer:
ΔU = 2 mg h
Explanation:
In a spring mass system the potential energy is U = m g h
where h is measured from the equilibrium point of the spring
the potential energy at the highest point is
U₁ = m g h
the potential energy at the lowest point is
U₂ = m g (-h)
instead in this energy it is
ΔU = 2 mg h
In this two points the kinetic energy is zero, but there is elastic potential energy that has the same value in the two points, so its change is zero
Answer:
acceleration
Explanation:
The rate at which velocity changes is the definition of the physical quantity called acceleration, and it is given by the formula: 
where 
is the time that took to change from the initial velocity 
to the final velocity 
Answer:
Explanation:
The rod will act as pendulum for small oscillation .
Time period of oscillation
angular frequency ω = 2π / T
= 
b )
ω = 20( given )
velocity = ω r = ω l
Let the maximum angular displacement in terms of degree be θ .
1/2 m v ² = mgl ( 1 - cosθ ) ,
[ l-lcosθ is loss of height . we have applied law of conservation of mechanical energy .]
.5 ( ω l )² = gl( 1 - cos θ )
.5 ω² l = g ( 1 - cosθ )
1 - cosθ = .5 ω² l /g
cosθ = 1 - .5 ω² l /g
θ can be calculated , if value of l is given .
Answer:
6m/s
Explanation:
the original momentum = mass x velocity = 8x (60+10) = 560
momentum after = mass x velocity of the school bag + mass x velocity of the boy = 10x20 + 60x A
200+60A = 560
A=6
