A Weightlifter Picks Up A Barbell

A weightlifter lifts the barbell and lifts it to chest level, holds it for 5 minutes, applies ...? 3

1. A weightlifter lifts a barbell and lifts it to chest level, holds it for 5 minutes and holds it in position. Rate the workload of the weight lifter in these three operations. Label landfills as W1, W2 and W3. Justify your order.

2. Estimate the work done on the 1,200 kg mass car since January when it was accelerated to 1.2 m / s2 at a distance of 150 m.

3. A real roller coaster that starts at point A and rides without an external power supply will follow the same path as in Figure 5. In the real world, lumbering elephants are exposed by the aggression of speeding midgets. If we refer to the total energy at point A as ground Uo, what can we say about the total energy and kinetic energy UB, the point UB at point B and the total energy and kinetic energy UC at UC?

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4. One gallon of gasoline has 1.3 x 108 joules of energy. A car weighing 2000 kg stops at a speed of 20 meters per second. Calculate the amount of petrol needed to return the car to the original SD. To complicate matters further, consider that only 15% of the energy produced by gasoline actually powers the car. The rest is used in the form of non-combustible heat and electricity.

I don't know if this is true or not, but I have ... it will be w1.

There are 0 functions in lding because there is no change in x, so x = 0, so the calculation is 0. So w3 and w2 explain the wait.

Other people might argue that Putin's weight is negative, so it should be last, but in theory I think it's always greater than 0 because it has a number.

f = 1200 kg * 1.2 m / s 2 = 1440

d = 150 meters

w = fdcos0 = fd

1440 * 150 = 216000J

Well, in ub, the kinetic energy and the total energy in 5050 are equal because half the size of the mountain point, so the total energy is 25%, while the kinetic energy is 25% because it is much smaller than point A. .

12.34 kg / calorie

A Weightlifter Picks Up A Barbell