Answer:
W = 20 J
Explanation:
Given that,
The mass of a loaded sack, m = 1000 g = 1 kg
It falls down from the floor of a lorry 200 cm high, h = 2 m
We need to find the work done by the gravity. The work done by an object under the action of gravity is given by :
W = mgh
Substitute all the values,
W = 1 × 10 × 2
= 20 J
Hence, the required work done by gravity is equal to 20 J.
The mechanical energy isn't conserved. Some energy is lost to friction.
Option A.
<h3><u>Explanation:</u></h3>
The mechanical energy is defined as the energy of a body which it achieves by virtue of its position and velocity. The mechanical energy are of two types - potential energy and kinetic energy. The potential energy is the energy of the body which it achieves by means of its relative position and is directly proportional to the height of the body from its relative plane. Whereas the kinetic energy of the body is achieved by virtue of its velocity and is directly proportional to the square of velocity of the body.
As the mountaineer is skiing down the slope of a mountain, the potential energy of the person is gradually changing into his kinetic energy. Had it been in an ideal situation, the potential energy lost would have been just equal to the kinetic energy gained by the person. But there's friction which opposes the speed of the body and reduces the velocity. Thus the kinetic energy will be lost to some extent and the energy won't be conserved.
Form concentric circles around the wire
Answer:
1.35 kJ
Explanation:
KE = ½mv² = ½ × 0.030 kg × (300 m·s⁻¹)² = 1350 J = 1.35 kJ
