Answer:
3.24 m/s
Explanation:
Suppose that the boat sails with velocity (relative to water) direction being perpendicular to water stream. Had there been no water flow, it would have ended up 0m downstream
Therefore, the river speed is the one that push the boat 662 m downstream within 539 seconds. We can use this to calculate its magnitude

So the boat velocity vector relative to the bank is the sum of of the boat velocity vector relative to the water and the water velocity vector relative to the bank. Since these 2 component vectors are perpendicular to each other, the magnitude of the total vector can be calculated using Pythagorean formula:
m/s
Answer:
Range of arrow = 225.09 meter
Final horizontal velocity = 34.47 m/s
Explanation:
We have equation of motion
, where u is the initial velocity, t is the time taken, a is the acceleration and s is the displacement.
Considering the vertical motion of arrow ( up direction as positive)
We have u = 45 sin40 = 28.93 m/s, s = -20 m, a = acceleration due to gravity =
.

t = 6.53 seconds or t = -0.63 seconds
So time = 6.53 seconds.
Considering the horizontal motion of arrow
u = 45 cos 40 = 34.47 m/s, t = 6.53 s, a = 

So range of arrow = 225.09 meter
Horizontal velocity will not change , final horizontal velocity = 34.47 m/s.
Answer:
a) v = √ 2gL abd b) θ = 45º
Explanation:
a) for this part we use the law of conservation of energy,
Highest starting point
Em₀ = U = mg h
Final point. Lower
Em₂ = ½ m v²
Em₀ = Em₂
m g h = ½ m v²
v = √2g h
v = √ 2gL
b) the definition of power is the relationship between work and time, but work is the product of force by displacement
P = W / t = F. d / t = F. v
If we use Newton's second law, with one axis of the tangential reference system to the trajectory and the other perpendicular, in the direction of the rope, the only force we have to break down is the weight
sin θ = Wt / W
Wt = W sin θ
This force is parallel to the movement and also to the speed, whereby the scalar product is reduced to the ordinary product
P = F v
The equation that describes the pendulum's motion is
θ = θ₀ cos (wt)
Let's replace
P = (W sin θ) θ₀ cos (wt)
P = W θ₀ sint θ cos (wt)
We use the equation of rotational kinematics
θ = wt
P = Wθ₀ sin θ cos θ
Let's use
sin 2θ = 2 sin θ cos θ
P = Wθ₀/2 sin 2θ
This expression is maximum when the sine has a value of one (sin 2θ = 1), which occurs for 90º,
2θ = 90
θ = 45º
Answer:
False
Explanation:
A compass can be used to determine relative direction but not absolute direction.
specific gravity of the unknown sample = 2.68
Explanation:
True weight of solid=31.6 N
Apparent weight=19.8 N
loss in weight= 31.6-19.8=11.8 N
Loss in weight= weight of the liquid displaced
so weight of water displaced= 11.8 N
now specific gravity= weight of object/ weight of liquid displaced
specific gravity= 31.6/11.8
specific gravity= 2.68