Sometimes, you can play sport for a longer time than you should. You should always stop and take a little break and always drink water. Also, if something starts to hurt, stop, let someone responsible know and take a break.
Answer:
Option d) only its mechanical energy is conserved
Explanation:
Since, mechanical energy of a system is the sum of its kinetic energy and potential energy.
Potential energy depends directly on height while kinetic energy depend on the speed of the body.
When the rock is dropped its potential energy decreases while its kinetic energy increases while the potential energy is maximum at the top and kinetic energy was zero.
Therefore, these two energies are inter convertible and when one increases the other decreases and vice-versa keeping the overall mechanical energy conserved.
Answer:
d = 136.7 ft
Explanation:
Because the truck move with uniformly accelerated movement we apply the following formula:
vf²=v₀²+2*a*d Formula (1)
Where:
d:displacement in meters (ft)
v₀: initial speed in ft/s
vf: final speed in ft/s
a: acceleration in ft/s²
Data
v₀ = 44.0 mi/h
1milla = 5280 ft
1h = 3600 s
v₀ = 44*(5280 ft) / (3600 s) = 64.5 ft/s
vf = 0
d = 47.0 ft
Calculation of the acceleration of the truck
We replace data in the formula (1) :
vf²=v₀²+2*a*d
0 = (64.5)²+2*a*(47)
-(64.5)² = (94)*a
a = -(64.5)² / 94
a = - 44.26 ft/s²
The acceleration (a) it's negative (-) because the truck is braking
Calculation of the minimum stopping distance of the truck to v₀ = 75.0 mi/h
v₀ = 75 mi/h = 75* (5280 ft) / (3600s) = 110 ft/s
We replace v₀ = 110 ft/s and a = - 44.26 ft/s² in the formula (1):
vf²=v₀²+2*a*d
0 = (110)²+2*(-44.26)*d
88.52*d = (110)²
d = (110)² / (88.52)
d = 136.7 ft