Answer:Racquet force is twice of Player force
Explanation:
Given
ball arrives at a speed of 
ball returned with speed of 
average Force imparted by racquet on the ball is given by

where 
time of contact of ball with racquet


When it land on the player hand its final velocity becomes zero and time of contact is same as of racquet


From 1 and 2 we get

Hence the magnitude of Force by racquet is twice the Force by player
Answer:
A. 26.17 B. 1.17 C. 30.86 D. 5.86
Explanation:
To solve the problem it is necessary to apply the concepts related to the conservation of energy through the heat transferred and the work done, as well as through the calculation of entropy due to heat and temperatra.
By definition we know that the change in entropy is given by

Where,
Q = Heat transfer
T = Temperature
On the other hand we know that by conserving energy the work done in a system is equal to the change in heat transferred, that is

According to the data given we have to,




PART A) The total change in entropy, would be given by the changes that exist in the source and sink, that is



On the other hand,



The total change of entropy would be,



Since
the heat engine is not reversible.
PART B)
Work done by heat engine is given by



Therefore the work in the system is 100000Btu
Answer:
1.21
Explanation:
Heat rise in the body happens due to heat supplied by water to the body.
Heat rise in body = m₁ c₁ ΔT₁
Where m₁ is mass of body and c₁ is its specific heat of body
Heat lost from water to the body = m₂ c₂ ΔT₂
Where m₂ is mass of water and c₂ is its specific heat of water ( c₂ =1 (since water))
Equating both:
15.3 x c₁ x 4.3 = 80.2 x 1 x 4.3
⇒ c₁ = 80.2 / (15.3 x 4.3) = 1.21
Answer:
. Doppler ultrasound is based on absorption of sound, and other
ultrasound technology is based on reflection.D.
Explanation: