Answer:
Force exerted, F = 1.5 N
Explanation:
It is given that, a boxer punches a sheet of paper in midair and brings it from rest up to a speed of 30 m/s in 0.060 s.
i.e. u = 0
v = 30 m/s
Time taken, t = 0.06 s
Mass of the paper, m = 0.003 kg
We need to find the force the boxer exert on it. The force can be calculated using second law of motion as :
F = 1.5 N
So, the force the boxer exert on the paper is 1.5 N. Hence, this is the required solution.
(B) 2.25cm
<u>Explanation:</u>
Given:
At 40 hours, the height of the bamboo plant is 2.1cm
At 50 hours, the height of the bamboo plant is 2.4cm
Height of the bamboo plant after 45 hours = ?
The difference in length from 40 to 50 hours = 2.4 - 2.1cm
= 0.3 cm
Mean of 40 and 50 is 45.
Thus,
At 45 hours, the height will increase by 0.3/2
= 0.15 cm
Height at 45 hour = 2.1 + 0.15cm
= 2.25cm
Therefore, the height of the plant after 45 hours is 2.25cm
Answer:
C
Explanation:
First find the electrical wattage
W = I^2 * R
R = 12 ohms
I = 2 amps
Wattage = 2^2 * 12
Wattage = 4* 12
Wattage = 48 watts.
Now you need to use the power formula
Work = Power * Time
Work = ?
Power = 48 watts
Time = 3 minutes = 3 * 60 = 180 seconds.
Work = 48 * 180
Work = 8640 J
That's C
The heat from your hand causes the ice molecules to heat up and become more active. This lowers the stability of the ice cube compound causing it to melt.
Time period = 1 / frequency
Time period = 1 / 250 th of a second
