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4 years ago

a train travels 99 kilometers in 3 hours, and then 80 kilometers in 5 hours. What is it’s average speed?

Physics

1 answer:

Karolina [17]4 years ago

6 0

Average speed = (total distance covered) / (time to cover the distance)

Total distance covered = (99km + 80km) = 179 km

Time to cover the distance = 8 hours

Average speed = (179km / 8hours)

Average speed = 22.375 km/hour

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A force of 200N due South and another force of 300N due East each act on an object simultaneously.

dangina [55]

Answer:

a) 500

b)-500, north west

Explanation:

a) sum of F= F1+F2= 200+300= 500

b) sum of forces=0

so 200+300-500+0

4 0

2 years ago

A rock falls 15 m. is this vertical or horizontal motion? what is the displacement?

Irina-Kira [14]

Displacement will be 15 too because
It falls from 0 till 15 meters

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4 years ago

A seesaw is 4.0m long with a pivot at its midpoint. A boy who weighs 400N sits at a distance of 1.5m from the pivot. His sister

bezimeni [28]

Answer:

the girl must sit 2 cm from the pivot at the opposite end of the seesaw.

Explanation:

Given;

length of the seesaw, L = 4.0 m

weight of the boy, W₁ = 400 N

position of the boy from the pivot, d₁ = 1.5 m

weight of her sister, W₂ = 300 N

First, make a sketch of this information given;

0---0.5m---------------------Δ--------------------------4m

↓<--------1.5m-------> <---------x--------->↓

400 N 300N

Apply the principle of moment about the pivot, to determine the value of x;

Sum of anticlockwise moment = sum of clockwise moment

400(1.5) = 300(x)

600 = 300x

x = 600/300

x = 2 cm

Thus, the girl must sit 2 cm from the pivot at the opposite end of the seesaw.

8 0

3 years ago

7. Katie and her best friend liam play tennis every saturday morning. When katie serves the ball to liam, it travels 9.5 meters

Ksenya-84 [330]

Answer:

The velocity of the tennis ball is 4.52 m/s.

Explanation:

Given that,

The distance covered by ball, d = 9.5 meters (due south)

Time, t = 2.1 sec

Let v is the velocity of the tennis ball. We know that the velocity of an object is given by the total distance covered divided by total time taken. It is given by :

$v=\dfrac{d}{t}\\\\v=\dfrac{9.5\ m}{2.1\ s}\\\\v=4.52\ m/s$

So, the velocity of the tennis ball is 4.52 m/s. Hence, this is the required solution.

6 0

3 years ago

Choose the correct statement regarding energy production in the interior of a star and energy production in a power plant. A sta

sergij07 [2.7K]

Answer:

A star uses fusion as an energy source by building larger atoms from smaller atoms.

Explanation:

Nuclear fission and fusion are two processes at which an atomic nucleus is changed to produce energy. Fission is the process splitting heavy atomic into lighter atomic nuclei.

So, fusion is the combination of smaller atoms to form larger atoms and star uses this as source of energy.

Fusion is the process at which light atomic nuclei are merged or fused together to form heavier nuclei.

The energy source for all stars is nuclear fusion. In a nuclear fusion reaction, the nuclei of two atoms combine to create a new atom. Most commonly, in the core of a star, two hydrogen atoms fuse to become a helium atom.

8 0

4 years ago

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