Force = mass × accelaration
Force = 0.25Kg × 196 m/s²
Force = 49 Newtons
<span>assuming the pitch is 100yards long, the player runs 100yards to the other goal then a further 50 yards back to the 50-yard line. So he/she runs 150yards in 18s
150/18 = 8.33yards per second average speed.
Initial velocity = 0, average velocity =8.33
Vav = (Vinitial+Vfinal)/2
Vav = 4.16m/s</span>
The total momentum of the system is preserved through the collision.
Note that momentum is
P = m*v
where m = mass
v = velocity.
Initial momentum:
P1 = (30000 kg)*(2 m/s) = 60000 (kg-m)/s for the moving car
P2 = 0 for the starionary car.
Final momentum:
P3 = (30000 + 30000)*v = 60000v (kg-m)/s
Because momentum is preserved,
P3 = P1 + P2
60000v = 60000
v = 1 m/s
The final velocity is 1 m/s.
Answer: 1.0 m/s
Refer to the diagram shown below.
The net force acting on the box is 17 - 13 = 4 N to the right.
The box moves on a friction surface by 3.5 m to the right.
By definition,
Work = Force x Distance.
(a) The work done by the girl is
W₁ = (17 N)*(3.5 m) = 59.5 J
(b) The work done by the boy is
W₂ = (13 N)*(-3.5 m) = - 45.5 J
(c) The work done by the net force is
W₃ = (4 N)*(3.5 m) = 14 J
Note that W₃ = W₁ + W₂
Answers:
(a) 59.5 J
(b) - 45.5 J
(c) 14 J