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3 years ago

7

500 J of work are done in 4 seconds to lift a 40 kg box to the top of a high shelf. How much power was required to complete the

lift?

1 answer:

Artemon [7]3 years ago

5 0

Answer:

125 W

Explanation:

Power = work / time

P = 500 J / 4 s

P = 125 W

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The gradient of a displacement-time graph gives

Drupady [299]

Answer:

Velocity

Explanation:

The gradient= change in velocity

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Change in time

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4 years ago

What cloud makes hail

MArishka [77]

Answer:

Cumulonimbus

Hail development. Hail is a type of strong precipitation, which is shaped in rainstorms mists (Cumulonimbus). Tempests mists comprises of beads of fluid water (at temperatures lower than 0°с, the beads can be in a thermodynamically instable supercooled condition) and ice gems

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3 years ago

Determine the kinetic energy of the ball immediately after it is hit. (You must provide an answer before moving to the next part

earnstyle [38]

The question is incomplete. Here is the complete question.

A baseball palyer hits a 5.1 oz baseball with an initial velocity of 140ft/sat an angle of 40° with the horizontal as shown. Determine

a) The kinetic energy of the ball immediately after it is hit

b) The kinetic energy of the ball when it reaches its maximum height

c) The maximum height above the ground reached by the ball.

Answer: a) KE = 131.64 J

b) KE = 0

c) h = 126 ft

Explanation: <u>Kinetic</u> <u>energy</u> is the energy an object posses due to its motion. It can be calculated as $KE=\frac{1}{2}mv^{2}$

a) Kinetic energy's unit is Joule. So, we have to transform ounce in kg and ft/s in m/s for the units to correspond:

m = 5.1(0.02835)

m = 0.1445 kg

v = 140 ft = 42.67 m/s

Then, kinetic energy is

$KE=\frac{1}{2}(0.1445)(42.67)^{2}$

KE = 131.64 J

Kinetic energy immediately after the ball is hit is 131.64 J.

b) At its maximum height, the ball has its highest potential energy. Because of the law of conservation of energy, when potential energy is maximum, kinetic energy is minimum and vice-versa. So, at the maximum height, kinetic energy is 0.

c) This type of motion is <u>projectile</u> <u>motion</u>. The maximum height on a projectile motion can be determined by

$v_{y}^{2}=v_{0y}^{2}-2g\Delta y$

When h is maximum, $v_{y}=0$

Velocity of the ball has an angle with the horizontal, so initial velocity at the y-axis is

$v_{0y}=v_{0}sin(\theta)$

Substituting and solving

$v_{y}^{2}=v_{0}^{2}sin^{2}(\theta)-2gh$

$0=(42.67)^{2}sin^{2}(40)-2(9.8)h$

$19.6h=(42.67)^{2}(0.643)^{2}$

$h=\frac{(1820.73)(0.4132)}{19.6}$

h = 38.4 m

Transforming into ft: h = 126 ft

The maximum height above the ground reached by hte ball is 126 feet.

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3 years ago

Why are neutral objects attracted to charged objects?

kow [346]

Explanation:

When neutral objects are placed in the vicinity of charged objects,they get attracted.

The isolated neutral object has positive charge and negative charge spread throughout it completely.

When a charged particle is brought,the opposite charges in the neutral object occupy the positions near to the charged particle and the like charges occupy the positions far from the charged particle.

This creates a dipole with some dipole moment.

This dipole attracts to the field of the charged particle.

5 0

4 years ago

You drive a car for 2.0 h at 60 km/h, then for another 3.0 h at 85 km/h. What is your average velocity

Anon25 [30]

Answer:

Explanation:

Average velocity is found in the total displacement experienced in the trip divided by the total time it took to make this trip. If, for the first 2.0 hours, the car travels at 60 km/hr, then in 2.0 hours the car can travel 120 km; if it then travels for 3.0 at 85 km/hr, it can travel 255 km in the same direction. The total time this took was 5.0 hours. So doing the math and rounding correctly by following the rules for the adding and subtracting of sig fig's:

$v=\frac{120+255}{5.0}=\frac{380}{5.0}=76\frac{km}{hr}$

If you do not round when you add, the average velocity is 75 km/hr

8 0

3 years ago