I couldnt type it out so here's a picture
Answer:
She must be launched with minimum speed of <u>57.67 m/s</u> to clear the 520 m gap.
Step-by-step explanation:
Given:
The angle of projection of the projectile is,
°
Range of the projectile is,
m.
Acceleration due to gravity, 
The minimum speed to cross the gap is the initial speed of the projectile and can be determined using the formula for range of projectile.
The range of projectile is given as:

Plug in all the given values and solve for minimum speed,
.

Therefore, she must be launched with minimum speed of 57.67 m/s to clear the 520 m gap.
Answer:
(a) The speed is 7.96 m/s
(b) The direction is 76 degree from positive X axis in counter clockwise direction.
Explanation:
Width of river = 280 m
speed of river, vR = 4.7 m/s towards east
speed of boat with respect to water, v(B,R) = 7.1 m/s at 26 degree west of north

(a) The velocity of boat with respect to ground is

(b) The direction is given by

The answer is A. the same.
Since the container is sealed, their will be no loss of material from the container which means that the mass won’t vary.