<span>h ( t) = h(1 sec) = -16t^2 + 541
so h (2 sec) = -16*(2)^2 + 541 = -64 + 541 = <span>477 ft
Therefore, </span></span>the height of the rock after 2 seconds is 477 feet.
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Answer:
KE = 1/2 * m * 
Explanation:
use the formula:
KE = 1/2 * m * 
KE = kinetic energy in joules (J)
m = mass in kg
v = velocity in m/s
F=ma therefore 25kg*1.0m/s^2=25N force on the mass
Answer:
200 mL
Explanation:
Given that,
Initial volume, V₁ = 300 mL
Initial pressure, P₁ = 0.5 kPa
Final pressure, P₂ = 0.75 kPa
We need to find the final volume of the sample if pressure is increased at constant temperature. It is based on Boyle's law. Its mathematical form is given by :

V₂ is the final volume

So, the final volume of the sample is 200 mL.
1. Answer: A skydiver whose air resistance is equal to that of her weight.
A skydiver free falls under gravity but her rate of fall slows down due to drag -air resistance. when this air resistance becomes equal to her weight, the two get balanced and the body does not accelerate or decelerates.
2. Answer: Gravity
Contact forces are those which act when there is physical contact between two bodies. For example: normal force, tension and spring force.
Non-contact forces act between two bodies even when they are at a distance apart. For example: gravity, electric force, magnetic force etc.
3. Answer: The tendency of an object's motion to remain the same.
Inertia is a property of matter by virtue of which it tends to remain in its state of motion or rest. It does depend on mass of the object, more the mass, more is inertia. For example, cycle can be easily moved but we need real push hard for a car to move.
4. Answer: 254 N
The man pushes the box with 310 N force at an angle of 55 degrees to the horizontal.
we can write this in terms of horizontal (
)and vertical component (
).
Horizontal component: 
Vertical component: 
The vertical component would act towards the floor making the job more difficult to move the job.