Answer:
13.5 J
Explanation:
mass of ball, m = 3 kg
maximum height, h = 2.8 m
initial speed, u = 8 m/ s
Angle of projection, θ
use the formula of maximum height


Sin θ = 0.926
θ = 67.8°
The velocity at maximum height is u Cosθ = 8 Cos 67.8 = 3 m/s
So, kinetic energy at maximum height

K = 0.5 x 3 x 3 x 3
K = 13.5 J
Density= mass/volume
in this case density= 1.1g
and the volume = 40 cm^3
so
1.1=40/mass
mass=40/1.1
mass=36.4
Answer:
Rachel(2.5,0)
ball(6.5,4.7)
b.R=10.15m/s, 27.57deg
Explanation:
The reference angle of Rachel is 0
resolving rachel's speed to the horizontal, we have
Ux=2.5cos0
Ux=2.5m/s
resolving rachel's speed to the vertical we have,
Uy=2.5sin0
Uy=0
for the ball
resolving the speed to its horizontal component
Ux=8cos36
Ux=6.5m/s
Uy=8sin36
Uy=4.7m/s
Rachel(2.5,0)
ball(6.5,4.7)
To get the resultant of their speed
Add the horizontal speed of rachel to that of the ball to get the total horizontal speed
Add the vertical speed of rachel and the ball to get the total vertical speed component
TUx=2.5+6.5=9M/S
TUy=0+4.7=4.7m/s
R=
R=
R=
R=10.15m/s
the direction
tan
=TUy/TUx
tan
=4.7/9
=tan^-1(0.522)
=27.57deg
The highest point of a wave is called the crest. Among the choices, the correct answer is C. The height of the wave can be determined using the crest and the trough. The trough is the lowest point of a wave. The wavelength is the distance between two crests of a wave.