Answer:
Total kinetic energy of entire system is 3 mgl
Explanation:
Given two masses: m and 4m.
Since the pulley is frictionless and the thread is massless, the energy here is linked to the two masses.
Total kinetic energy of entire system = decrease in gravitational potential energy of the system.
Therefore, we have :
ΔKE = Δp
ΔKE = 4mgl - mgl
= 3 mgl
Total kinetic energy of entire system is 3 mgl
Answer:
Writing with a pencil. The pencil pushes on the paper. The paper pushes on the pencil.
Explanation:
Newton's third law.
Answer:
His machine must increase
Explanation:
The total mechanical energy of the block-spring system is given by the sum of the potential energy and the kinetic energy of the block:

where
k is the spring constant
x is the elongation/compression of the spring
m is the mass of the block
v is the speed of the block
At the point of maximum displacement of the spring, the velocity of the block is zero: v=0, so the kinetic energy is zero and the mechanical energy is just potential energy of the spring:

(1)
where we used x=A, the amplitude (which is the maximum displacement of the spring).
Since we know
A = 11.0 cm= 0.11 m
E = 1.10 J
We can re-arrange (1) to find the spring constant: