In Figure 1 , an engine that delivers power P is attached to a pulley that lifts a box of mass m0 a vertical distance of y0 at a constant speed in time t0 . If, as shown in Figure 2 the engine again delivers power P , how long would it take the engine to raise a box of mass 3m0 the same vertical distance y0 at a constant speed? Options:
1/3 t0
t0
root(3 t0
3t0
9t0

t = 3 t₀

Explanation:

The formula for the power delivered by the engine can be given in terms of the change in the potential energy of the box as follows:

P = P.E/t = mgy/t

where,

P = Power delivered by the engine

m = mass of box lifted = m₀

g = acceleration due to gravity

y = vertical distance or height box covered = y₀

t = time taken = t₀

Therefore,

P = m₀gy₀/t₀

t₀ = m₀gy₀/P   equation (1)

Now, if we change the mass of box as:

m = 3m₀

y = y₀ (constant)

P = Constant

Then,

P = 3m₀gy₀/t

t = 3m₀gy₀/P

using equation (1):

t = 3 t₀

the focus of lesson 1 is newton's first law of motion - sometimes referred to as the law of inertia. newton's first law of motion is often stated as. an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

explanation:

a cold ice-tea.

pour in room temperature or cold water. cover the pitcher and refrigerate. steep white or green tea for 6 to 8 hours; steep black or oolong tea for 8 to 12 hours.jun 28, 2015