1.A and 2.B there the answers
The power is 833.3 W
Explanation:
First of all, we need to calculate the work done in lifting the barbell, which is equal to the change in gravitational potential energy of the barbell:

where
mg = 1250 N is the weight of the barbell
h = 2 m is the change in height
Substituting,

Now we can calculate the power, which is equal to the work done per unit time:

where
W = 2500 J is the work done
t = 3 s is the time taken
Substituting,

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Answer:
The minimum total speed is 11.2km/s
Explanation:
We are been asked to find the escape velocity.
Escape velocity is defined as the minimum initial velocity that will take a body(projectile)away above the surface of a planet(earth) when it's projected vertically upwards.
The formula to calculate the escape velocity is Ve = √2gR
For the earth g = 9.8m/s2 , R = 6.4*10^6
Substituting into the equation Ve = √2*9.8*6.4*10^6 = 11.2*10^3m/s
=11.2km/s
All of the above, work is a measurement of energy transfer, in Joules.
Potential energy = Joules
Kinetic energy = Joules
The key thing here is that anything having to do with just energy or energy transfer is measured in joules.
Answer:
Cruising at 35,000 feet in an airliner, straight toward the east,
at 500 miles per hour
Explanation: