Answer:
The force must he apply to the sled is of F= 764.4 N.
Explanation:
m= 60 kg
g= 9.8 m/s²
μ=0.3
W= m*g
W= 588 N
Fr= μ*W
Fr= 176.4 N
F= W + Fr
F= 764.4 N
Answer:
The ball will be at 700 m above the ground.
Explanation:
We can use the following kinematic equation
.
where y(t) represent the height from the ground. For our problem, the initial height will be:
.
The initial velocity:
,
take into consideration the minus sign, that appears cause the ball its thrown down. The same minus appears for the acceleration:

So, the equation for our problem its:
.
Taking t=6 s:
.
.
.
.
.
So this its the height of the ball 6 seconds after being thrown.
Answer:
Potential energy of book = 7.5 J
Explanation:
Given:
Weight of book = 5 N
Height of shelf = 1.5 meter
Find:
Potential energy of book
Computation:
Weight = Mass x Acceleration of gravity
Mass x Acceleration of gravity = 5 N
Potential energy = Mass x Acceleration of gravity x Height
Potential energy of book = Mass x Acceleration of gravity x Height
We know that;
Mass x Acceleration of gravity = 5 N
So,
Potential energy of book = 5 x 1.5
Potential energy of book = 7.5 J
Use kinematic equations to solve:
1) yf = yo + vo*t + 1/2at²
yf = final height
yo = initial height
vo = initial velocity
a = acceleration
t = time
yf - yo = vo*t + 1/2at²
yf - yo = h
vo = 0
Thus,
h = 1/2at²
h = 1/2(9.8)(12)² = 705.6 m
2) vf = vo + at
vo = 0
Thus,
vf = at
vf = (9.8)(12) = 117.6 m/s