It IS <span>PE = (1200 kg)(9.8 m/s²)(42 m) = 493,920 J </span>
Answer:
A
C
D
B
Explanation.
At point A The body is at rest so k.E is zero but the height is maximum so that p.E is max.
Answer:
The amount of work done required to stretch spring by additional 4 cm is 64 J.
Explanation:
The energy used for stretching spring is given by the relation :
.......(1)
Here k is spring constant and x is the displacement of spring from its equilibrium position.
For stretch spring by 2.0 cm or 0.02 m, we need 8.0 J of energy. Hence, substitute the suitable values in equation (1).

k = 4 x 10⁴ N/m
Energy needed to stretch a spring by 6.0 cm can be determine by the equation (1).
Substitute 0.06 m for x and 4 x 10⁴ N/m for k in equation (1).

E = 72 J
But we already have 8.0 J. So, the extra energy needed to stretch spring by additional 4 cm is :
E = ( 72 - 8 ) J = 64 J
Answer: R = 0.131 m
Explanation: The formulae for the distance between a fringe and the first (center) is given by
y = R×mλ/d
Where y = distance between first and nth fringe = 4mm = 4×10^-3m
λ = wavelength of light = 441.1nm = 441.1×10^-9m
R = distance between slits and screen =?
d = distance between slits = 0.29mm = 2.9×10^-4m
4×10^-3 = R ×2 ×441.4×10^-9/ 2.9×10^-5
Hence R = (4×10^-3) ×(2.9×10^-5)/2×441.4×10^-9
R = 1.16 × 10^-7/8.828×10^-7
R = 1.16/8.828
R = 0.131 m
Answer:
Because of heavy mass
Explanation:
When force acts on a body it tends to accelerate the body. The acceleration produced in the body depends on two things:
1). Magnitude of force
2). Mass of the body
F= ma
⇒ a = F/m
As the force exerted on earth and another object are the equal in magnitude but opposite in direction. This forces will accelerate the object toward the earth but can't accelerate the earth as earth has very high mass.
a = F/m
This force tends to accelerate the earth but but due to earth's inertia the earth does not accelerate.