Here's a formula that's simple and useful, and if you're really in
high school physics, I'd be surprised if you haven't see it before.
This one is so simple and useful that I'd suggest memorizing it,
so it's always in your toolbox.
This formula tells how far an object travels in how much time,
when it's accelerating:
Distance = (1/2 acceleration) x (Time²).
D = 1/2 A T²
For your student who dropped an object out of the window,
Distance = 19.6 m
Acceleration = gravity = 9.8 m/s²
D = 1/2 G T²
19.6 = 4.9 T²
Divide each side by 4.9 : 4 = T²
Square root each side: 2 = T
When an object is dropped in Earth gravity,
it takes 2 seconds to fall the first 19.6 meters.
I think the correct answer from the choices listed above is option B. When calculating the power bill, power companies use kilowatt-hours. This unit is a derived unit of energy equal to 3.6 MJ. If energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time.
Answer:
Explanation:
When we apply a horizontal force of 76 N to a block, the block moves across the floor at a constant speed. So net force on the block is zero .
It implies that a force ( frictional ) acts on it which is equal to 76 N in opposite direction ( friction )
When we apply a greater force on it it starts moving with acceleration .
This time kinetic friction acts on it due to rough ground equal to 76 N .This is limiting friction ( maximum friction )
Net force on the body in later case
= 89 - 76
= 13 N
Force by ground on the block in horizontal direction = 76 N ( FRICTIONAL FORCE )
=
Answer:
11.48 m
Explanation:
A brick starts from rest and gains a speed of 15 m/s and accelerates at 9.8 m/s^2
u = 0
v= 15
a= 9.8
s= ?
V^2 = U^2 + 2as
15^2 = 0^2 + 2 × 9.8×s
225= 19.6s
s= 225/19.6
s = 11.48m
Hence the brick will fall 11.48 m
Answer:
221.17 kJ
Explanation: Note the heat of vaporization is in kJ/mol,then to determine the number of moles of water: divide the mass by 18. Then multiply the number of moles by the molar heat of vaporization of water.
N = 97.6 ÷ 18
Q=molar heat *moles
Q = (40.79) * (97.6 ÷ 18)
This is approximately 221.17 kJ