1.) The force of gravity is what we call weight, we define it as: w=mg w=5,7kg*9,8m/s² w=55,86kg (b) 2.) We know that: power=W/t power=50J/20s power=2,5Watts (a) 3.) The work done is equal to the potential energy, so: Epg=mgh Epg=63kg*9,8m/s²*7m Epg=4321J Now we get the power: power=W/t power=4321J/5s power=864Watts Now: 1HP=746Watts =1,16HP (b) 4.) We know that: F=ma 350N=m*10m/s² m=350N/10m/s² m=35kg (b) 5.) d.) Aceleration is tha rate of change in velocity, either positive (increasing) or negative (decreasing)
Weight = (mass) x (gravity) Work = (force) x (distance) Power = (work done) / (time to do the work)
So Power = (mass) x (gravity) x (distance) / (time to lift)
= (63 kg) x (9.8 m/s²) x (7 m) / (5 sec)
= (63 x 9.8 x 7) / (5) (kg-m²/s²) / (sec)
= 864.36 joules/sec
Convert (864.36 watts) x (1 HP/746 watts) = 1.159 HP
(How to remember the conversion from watts to Horsepower: The sails on Columbus' ship the Santa Maria developed 2 HP at top wind. 1492 / 2 = 746 watts per HP. )
==> A force of 350 N causes . . .
Force = (mass) x (acceleration)
Mass = (force) / (acceleration)
= (350 kg-m/s²) / (10 m/s²)
= 35 kg.
==> Which of the following . . .
Golden Rule: "Acceleration means any change in velocity, including change in speed or direction."
A). No. Constant velocity means zero acceleration. B). No. When people say "decelerating" they mean "slowing down". That's decreasing magnitude of velocity. C). Yes. 'Acceleration' does NOT mean 'speeding up'. Any change in speed or direction, even slowing down, is acceleration. D). Yes. If an object's velocity is changing, then either the speed or direction of its motion is changing, and either of those is 'acceleration'. The object doesn't need to be speeding up or slowing down, but if its direction is changing, then that's called 'acceleration. Rounding a curve at a constant speed, or driving a circle with constant speed, are both examples of 'acceleration'.
