Answer:
Speed, u = 29.4 m/s
Explanation:
Given that, A ball thrown straight up climbs for 3.0 sec before falling, t = 3 s
Let u is speed with which the ball is thrown up. When the ball falls, v = 0
Using first equation of motion as :
v = u + at
Here, a = -g
So, u = g × t

u = 29.4 m/s
So, the speed with which the ball was thrown is 29.4 m/s. Hence, this is the required solution.
Answer:The formula for kinetic energy is
(1/2) M V^2.
With M in kg and V in m/s, the answer will be in Joules.
K.E = 40joule
Explanation:
Explanation:
Given that,
(a) Frequency, 
All electromagnetic wave moves with the speed of light. It is given by :


(b) Frequency, 
All electromagnetic wave moves with the speed of light. It is given by :


Hence, this is the required solution.
Answer:
option A
Explanation:
given,
lamp position from pool wall = 2.5 m
height of the pool = 2.5 m
now,



from the triangle
θ = i = 45°
using Snell's law
n₁ sin i = n₂ sin r
n₁ =4/3 n₂ = 1
now,



r = sin⁻¹(0.9428)
r = 70.5°
hence, the correct answer is option A
Answer:
B
Explanation:
The correct option for the question is B that is salt water. In salt water, the density of water is higher so the pressure at the end of tube containing salt water will be greater. As according to the hydrostatic law the pressure at a given point will be directly proportional to the distance travelled as well.