In 2014, physicists from FOM Foundation at the University of Amsterdam introduced a new hypothesis of how the Pyramids at Giza were built. The group of physicists suggestedthat ancient Egyptians wetted sand in an effort toreduce friction and then pulled the 3000 kg stoneblocks to their final resting place. 15 men couldmove a block at a rate of 0.5m/sby pulling a largerope angled at 30owith respect to the plane anda tension of 7,200 N. Required:
a. What is net work done on block?
b. What is speed of blck after it moved .25m?
c. What is work done by block if kinetic friction coefficient is 0.3?
d. What is net work including friction?

The correct answer is:

(a) 0

(b) 0.5 m/s

(c) 7740 N

(d) 0

Explanation:

The given values are:

mass,

m = 3000 kg

Tension,

T = 7,200 N

Angle,

= 30°

(a)

Even as the block speed becomes unchanged, the kinetic energy (KE) will adjust as well:

⇒

By using the theorem of energy, the net work done will be:

⇒  

(b)

According to the question, After 0.25 m the block is moving with the constant speed

= 0.5 m/s.

(c)

The given kinetic friction coefficient is:

u = 0.3

The friction force will be:

=  

On substituting the values, we get,

=

=

=

=

(d)

On including the friction,

The net work will be:

⇒

a straight line sloped

gpe = mass x gravity constant x height or… gpe = mgh

where… mass: measured in kilograms (kg)

gravity: gravity constant on earth = 10.00 m/s2

height: measured in meters (m)

gpe: measured in joules (j) or kilojoules (kj)

how do you solve gpe?

gravitational potential energy (gpe) is the energy an object has because of its position above the. ground.

gpe = mass x gravity constant x height or… gpe = mgh.

mass:

note: to earn full marks when solving science word problems, you must show your work:

formula.

example:

given values:

mass = 0.3 kg.