His weight depends on where he is, because
Weight = (mass) x (gravity in the place where the mass is) .
For example:
-- If this man is on Mars, his weight is (110 kg) x (3.7 m/s²) = 408 Newtons
-- If he is on the Moon, his weight is (110 kg) x (1.6 m/s²) = 176 Newtons
-- If he is on Earth, his weight is (110 kg) x (9.8 m/s²) = 1,078 Newtons
-- If he is in a spacecraft coasting from one to another, his weight is zero.
Answer: 4.9 x 10^6 joules
Explanation:
Given that:
mass of boulder (m) = 2,500 kg
Height of ledge above canyon floor (h) = 200 m
Gravita-tional potential energy of the boulder (GPE) = ?
Since potential energy is the energy possessed by a body at rest, and it depends on the mass of the object (m), gravitational acceleration (g), and height (h).
GPE = mgh
GPE = 2500kg x 9.8m/s2 x 200m
GPE = 4900000J
Place result in standard form
GPE = 4.9 x 10^6J
Thus, the gravita-tional potential energy of the boulder-Earth system relative to the canyon floor is 4.9 x 10^6 joules
Answer:
Explanation:
During the first .8 s , the elevator is under acceleration . It starts from initial velocity u = 0 , final velocity v = 1.2 m /s , time = .8 s
v = u + at
1.2 = 0 + .8 a
a = 1.2 / .8
= 1.5 m /s²
During the acceleration in upward direction , let reaction force of ground on man be R .
Net force on man = R - mg
Applying Newton's 2 nd law
R - mg = ma
R = m ( g + a )
= 72 ( 9.8 + 1.5 )
= 813.6 N .
This reaction force will be measured by spring scale , so reading of spring scale will be 813.6 N .
Work done = force x distance = 40 x 2 = 80 Joules.
