a). The work done in holding a 50kg object at a height of 2 m above the floor for 10s is?
b). A total of 4900J is used to lift a 50-kg mass. The mass is raised to a height of?
c). A 1-kg object has kinetic energy of 1 J when its speed is?
2007-09-20 12:30:06 · 2 answers · asked by TwiggyRamirez 2 in Science & Mathematics ➔ Mathematics
The equations are:
Force = mass * acceleration
Work = force * distance.
Kinetic energy = (1/2) mass * velocity^2
If the mass is in kg, and the acceleration is in m/sec^2, and the distance is in metres, the force is in newtons and the work or energy is in joules.
When a force is expressed in kg. and you need to convert it to newtons, the factor to multiply by is g = 9.81 m/sec^2.
(a)
Work = force * distance moved
As the object is not moving, the distance is 0, and therefore the work is 0.
(b)
Work = force * distance
Let h be the required height.
Then:
4900 = (50 * 9.81) * h
h = 4900 / (50 * 9.81)
= 9.99 metres.
(c)
Kinetic energy = (1/2) mass * velocity^2.
Let v be the required speed.
Then:
1 = (1/2)(1)v^2
1 = v^2 / 2
v^2 = 2
v = 1.41 m/sec^2
2007-09-20 23:09:12 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Dream: fact Genius: Ignorant Latino: Senior: Junior dedication: Abandonment enable: Forbid start up: end embody: Push Summed: Subtracted Pursue: depart Greatness: constrained undesirable: wealthy nicely-enjoyed: undemanding damaging: advantageous Black: White
2016-10-09 13:36:37 · answer #2 · answered by Anonymous · 0⤊ 0⤋