A 9.50 {\rm g} bullet has a speed of 1.40 {\rm km/s}.
What is its kinetic energy in joules?
What is the bullet's kinetic energy if its speed is halved?
If its speed is doubled?
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To find the kinetic energy of the bullet, we can use the formula:
Kinetic energy = (1/2) * mass * velocity^2
Given:
Mass of the bullet = 9.50 g = 0.0095 kg
Velocity of the bullet = 1.40 km/s = 1400 m/s
1. Kinetic energy = (1/2) * mass * velocity^2
= (1/2) * 0.0095 kg * (1400 m/s)^2
≈ 11,766 J (Joules)
2. If the speed of the bullet is halved, the new velocity would be:
New velocity = 1400 m/s / 2 = 700 m/s
Kinetic energy (new) = (1/2) * mass * (new velocity)^2
= (1/2) * 0.0095 kg * (700 m/s)^2
≈ 2,358 J (Joules)
3. If the speed of the bullet is doubled, the new velocity would be:
New velocity = 1400 m/s * 2 = 2800 m/s
Kinetic energy (new) = (1/2) * mass * (new velocity)^2
= (1/2) * 0.0095 kg * (2800 m/s)^2
≈ 66,084 J (Joules)
To calculate the kinetic energy (KE) of an object, you can use the equation: KE = (1/2) * mass * velocity^2.
1. To find the kinetic energy of the 9.50 g bullet with a speed of 1.40 km/s, you need to convert the mass to kilograms and the speed to meters per second.
First, convert the mass from grams to kilograms:
mass = 9.50 g = 9.50/1000 kg = 0.0095 kg
Next, convert the speed from kilometers per second to meters per second:
speed = 1.40 km/s = 1.40 * 1000 m/s = 1400 m/s
Now you can substitute the values into the kinetic energy equation to calculate the bullet's kinetic energy:
KE = (1/2) * mass * velocity^2
= (1/2) * 0.0095 kg * (1400 m/s)^2
= 0.5 * 0.0095 kg * 1960000 m^2/s^2
= 9362 J (rounded to the nearest whole number)
Therefore, the kinetic energy of the bullet is approximately 9362 joules.
2. If the bullet's speed is halved, the new speed would be 1.40 km/s / 2 = 0.70 km/s. To calculate the new kinetic energy, we follow the same process as before:
First, convert the new speed from kilometers per second to meters per second:
new speed = 0.70 km/s = 0.70 * 1000 m/s = 700 m/s
Now, substitute the new speed into the kinetic energy equation:
KE = (1/2) * mass * new velocity^2
= (1/2) * 0.0095 kg * (700 m/s)^2
= 0.5 * 0.0095 kg * 490000 m^2/s^2
= 2207 J (rounded to the nearest whole number)
Therefore, if the bullet's speed is halved, its kinetic energy would be approximately 2207 joules.
3. If the bullet's speed is doubled, the new speed would be 1.40 km/s * 2 = 2.80 km/s. Again, we follow the same process:
First, convert the new speed from kilometers per second to meters per second:
new speed = 2.80 km/s = 2.80 * 1000 m/s = 2800 m/s
Now, substitute the new speed into the kinetic energy equation:
KE = (1/2) * mass * new velocity^2
= (1/2) * 0.0095 kg * (2800 m/s)^2
= 0.5 * 0.0095 kg * 7840000 m^2/s^2
= 35240 J (rounded to the nearest whole number)
Therefore, if the bullet's speed is doubled, its kinetic energy would be approximately 35240 joules.
You must know how to calculate kinetic energy by now.
K.E. = (1/2) M V^2
Make sure V is in m/s and M is in kg. That will give you the answer in Joules.
The other parts of the question I am sure you can figure out.