Answer:
f = 0.75 Hz
Explanation:
It is given that, a person is kicking there legs three times every four seconds. We need to find his frequency. The number of times an event is occurring is called frequency of an object. The frequency of a person is given by :

So, the frequency of the person is 0.75 Hz.
Answer:8.1 m
Explanation:
Given
ball is launched from height of 3 m
initial velocity 
considering the ball is thrown vertically upward
Using 
where,
u=initial velocity
v=final Velocity
a=acceleration
s=distance
At maximum height final velocity will be zero



Therefore maximum height w.r.t ground is 
Answer:
Explanation:
Total heat = Work done = Force × distance
distance = 0.075 × 12 = 0.9 m
W = 45 × 0.9 = 40.5 joules
Specific heat of the human hand = 3.5 kj/kg = 3.5 j/g
Q = MCΔT
ΔT = (Q) ÷ (MC)
ΔT = 40.5 ÷ (3.5 × 1) = 11.57°C
<span>The correct answer is B. - It would take a ray of light 10.5 light years to travel from Earth to Epsilon Eridani, or vice-versa. Using our current technology it would take far longer than 21.0 years for a space ship from Earth to travel that far - I would have to guess many hundreds of years.</span>