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Vika [28.1K]
3 years ago
6

A man is throwing a spear from the top of a cliff, 5 metres from ground, at a 20° angle towards a fish that is 35 metres away. a

t what Velocity must the person throw to hit the fish and how long will it take?​

Physics
1 answer:
svlad2 [7]3 years ago
6 0

Answer:

Horizontal component of the initial velocity=v ×cos20°

horizontal displacement= 35m

time taken. (t)=35÷(v×cos20°)

vertical component of the initial velocity= v×sin20°

vertical displacement= -5m(since it is opposite to the direction of the initial velocity. )

application of s=ut+1/2at×t. vertically,

-5=vsin20°×t -1/2 gt×t

-5= vsin20×35/vcos20-1/2×10×35×35/(vcos20×vcos20)

simplify further to obtain v and hence find the time taken

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2 objects have a total momentum of 400kg m/s, they collide. Object A’s mass is5kg & object B’s mass is 11kg. After the colli
ss7ja [257]

Answer:

Explanation:

We shall apply law of conservation of momentum .

Momentum before collision = momentum after collision .

Momentum before collision = 400 kg m/s

Momentum after collision = 5  x v + 11 x 15

where v is velocity of A after the collision .

5  x v + 11 x 15 = 400

5 v = 400 - 165

5v = 235

v = 47 m /s .

3 0
3 years ago
Three strings, attached to the sides of a rectangular frame, are tied together by a knot as shown in the figure. The magnitude o
Anna [14]

The magnitude of the tension in the string marked A is 52.5N

Generally, the equation for is mathematically given as

Let's take θ be an angle at A

So, tanθ = 3/8

Let's take α be an angle at B (Below X)

tanα = 5/4

Let's take β be an angle at C (Below x)

tanβ = 1/6

First we take the Horizontal Components

74.9cos(9.46°) = Acos(20.6°) + Bcos(51.3°)

By solving the equation, we get

A = 78.9 - 0.668B … (1)

Now, we take the vertical components

74.9sin(9.46°) + Asin(20.6°) = Bsin(51.3°)

By solving the equation, we get

40.07 = 1.015B

B = 39.5N

By substituting the value of B in equation (1)

A = 78.9 - 0.6668× 39.5

A = 52.5N

Hence, the magnitude of the tension in the string marked A is 52.5N

Learn more about Tension here brainly.com/question/2287912

#SPJ1

8 0
2 years ago
A 4.79 g bullet moving at 642.3 m/s penetrates a tree trunk to a depth of 4.35 cm. Use work and energy considerations to find th
vladimir1956 [14]

Answer:

Force, F=2.27\times 10^4\ N

Explanation:

Given that,

Mass of the bullet, m = 4.79 g = 0.00479 kg

Initial speed of the bullet, u = 642.3 m/s

Distance, d = 4.35 cm = 0.0435 m

To find,

The magnitude of force required to stop the bullet.

Solution,

The work energy theorem states that the work done is equal to the change in its kinetic energy. Its expression is given by :

F.d=\dfrac{1}{2}m(v^2-u^2)

Finally, it stops, v = 0

F.d=-\dfrac{1}{2}m(u^2)

F=\dfrac{-mu^2}{2d}

F=\dfrac{-0.00479\times (642.3)^2}{2\times 0.0435}

F = -22713.92 N

F=2.27\times 10^4\ N

So, the magnitude of the force that stops the bullet is 2.27\times 10^4\ N

7 0
2 years ago
Isaac Newton's first law of motion states?
lesya [120]

Answer:

His first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. In other words its  inertia.

Explanation:

8 0
3 years ago
7. Sally's mass on Earth is 50 kg. What is her weight on the moon?
Makovka662 [10]

Answer:

82.6

Explanation:

7 0
2 years ago
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