Answer:
B)60km[W]
Explanation:
The boat travels 20km/h. So every hour the boat goes 20 miles. So if one hour equals 20km. Then 3 hours will be 3*20km which equals 60km. The boat is also going west. So you should consider putting that in your answer as well. So the answer would be B)60km[W].
Hope that helps!
Answer:
96.7 s
Explanation:
Time of flight in projectile can be calculated thus:
T = 2 × u × sin ϴ/ g
Where;
T = time of flight (s)
u = initial velocity (m/s)
ϴ = Angle of projectile (°)
g = acceleration due to gravity (9.8m/s²)
Based on the provided information; u = 670m/s, ϴ = 45°
Hence, using T = 2.u.sin ϴ/ g
T = 2 × 670 × sin 45° ÷ 9.8
T = 1340 × 0.7071 ÷ 9.8
T = 947.52 ÷ 9.8
T = 96.68
T = 96.7s
We have the relation

where
denotes the velocity of a body A relative to another body B; here I use B for boat, E for Earth, and R for river.
We're given speeds


Let's assume the river flows South-to-North, so that

and let
be the angle made by the boat relative to East (i.e. -90° corresponds to due South, 0° to due East, and +90° to due North), so that

Then the velocity of the boat relative to the Earth is

The crossing is 153.0 m wide, so that for some time
we have

which is minimized when
so the crossing takes the minimum 30.0 s when the boat is pointing due East.
It follows that

The boat's position
at time
is

so that after 30.0 s, the boat's final position on the other side of the river is

and the boat would have traveled a total distance of

Answer:
So do 2400 divided by 70. I got 34.285714 and the numbers behind the decimal are repeating. If you round it you get 34.3
Answer:
-14.2m/s
Explanation:
Given parameters:
Initial velocity of the ball = 25m/s
Time = 4s
Unknown:
Final velocity of the ball = ?
Solution:
To solve this problem, we use the expression below;
v = u - gt
v is the final velocity
u is the initial velocity
g is the acceleration due to gravity
t is the time
v = 25 - (9.8 x 4) = -14.2m/s