A plane accelerates from 25 m/s to a velocity of 80 m/s in a time of 5 seconds. What
1 answer:
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Answer:
b. 0.20 m/s.
Explanation:
Given;
initial mass, m = 0.2 kg
maximum speed, v = 0.3 m/s
The total energy of the spring at the given maximum speed is calculated as;
K.E = ¹/₂mv²
K.E = 0.5 x 0.2 x 0.3²
K.E = 0.009 J
If the mass is changed to 0.4 kg
¹/₂mv² = K.E
mv² = 2K.E
Therefore, the maximum speed is 0.20 m/s
Answer:
354.72 m/s
Explanation:
= mass of lead bullet
= specific heat of lead = 128 J/(kg °C)
= Latent heat of fusion of lead = 24500 J/kg
= initial temperature = 27.4 °C
= final temperature = melting point of lead = 327.5 °C
= Speed of lead bullet
Using conservation of energy
Kinetic energy of bullet = Heat required for change of temperature + Heat of melting
Answer:
6.86 meters
Explanation:
Let the compression of the string be represented by x, and the height of projection of the toy rocket be represented by h.
So that;
x = 9 cm = 0.09 m
In its rest position (i.e before the launch), the spring has a stored potential energy which is given as;
PE = K
= x 830 x
= 415 x 0.0081
= 3.3615
The potential energy in the string = 3.36 Joules
Also,
PE = mgh
where: m is the mass, g is the gravitational force and h the height.
m = 50 g = 0.05 kg, g = 9.8 m
Thus,
PE = 0.05 x 9.8 x h
3.3615 = 0.05 x 9.8 x h
3.3615 = 0.49h
⇒ h =
= 6.8602
The height of the toy rocket would be 6.86 meters.