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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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A block is held at rest against a wall by a force of magnitude F exerted at an angle theta from the horizontal, as shown in the
wel

Answers:

B.) F cos\theta=F_{n}

C.) F sin\theta=F_{g} \pm F_{f}

Explanation:

The image attached shows the way the force F is acting on the block. Now, if we draw a free body diagram of the situation and write the equations for the Net Force in X and Y, we will have the following:

Net Force in X:

-F_{n}+F cos\theta=0 (1)

Where:

F_{n} is the Normal force

F is the magnitude of the force exerted on the block

\theta is the angle

Net Force in Y:

F sin\theta \pm F_{f}-F_{g}=0 (2)

Where:

F_{f} is the Friction force (it is expresed with the \pm sign because this force may be up or down, we cannot know because the block is at rest)

F_{g} is the gravity force

Rewrittin (1):

F cos\theta=F_{n} (3) This is according to option B

Rewritting (2):

F sin\theta=F_{g}\pm F_{f} (3) This is according to option C

3 0
3 years ago
What is the average speed if an object travels 200 km in 5 hours
melamori03 [73]

Answer:

40km per hour

Explanation:

8 0
3 years ago
How is 0.00069 written in scienitfic notation?
victus00 [196]
You need to move the decimal point between the six and nine. 6.9 X 10^-4
8 0
3 years ago
For a converging lens, a ray arriving parallel to the optic axis
mixer [17]

Answer:

b. passes through the principal focal point.

Explanation:

Light wave can be defined as an electromagnetic wave that do not require a medium of propagation for it to travel through a vacuum of space where no particles exist.

A lens can be defined as a transparent optical instrument that refracts rays of light to produce a real image.

Basically, there are two (2) main types of lens and these includes;

I. Diverging (concave) lens.

II. Converging (convex) lens.

A converging lens refers to a type of lens that typically causes parallel rays of light with respect to its principal axis to come to a focus (converge) and form a real image. This type of lens is usually thin at the lower and upper edges and thick across the middle.

For a converging lens, a ray arriving parallel to the optic axis passes through the principal focal point.

8 0
3 years ago
An ac generator consists of a coil with 40 turns of wire, each with an area of 0.06 m2. The coil rotates in a uniform magnetic f
Reptile [31]

Answer:

331.75 V

Explanation:

Given:

Number of turns of the coil, N = 40 turns

Area, A = 0.06 m²

Magnetic Field, B = 0.4 T

Frequency, f = 55 Hz

                           Maximum induce emf, E₀ = NABω

but ω = 2πf

                           Maximum induce emf, E₀ = NAB(2πf₀)

                           Maximum induce emf, E₀ = 2πNABf₀

Where;

N is number of turns of the coil

A is area

B is magnetic field

ω is the angular velocity

f is the frequency

                                     E₀ = 2 × π × 40 × 0.06 × 0.4 × 55

                                     E₀ = 342.81 V

The maximum induced emf is 331.75 V

6 0
3 years ago
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