Question

5. A truck starts from rest and rolls down a hill with a consta
acceleration. It travels a distance of 400 m in 20 s. Find its
acceleration. Find the force acting on it if its mass is
7 tonnes (Hint: 1 tonne = 1000 kg.)
6. A stone of 1 kg is thrown with a velocity of 20 m s-1 across
the frozen surface of a lake and comes to rest after travelling
a distance of 50 m. What is the force of friction between the
stone and the ice?​

Answer 1

Answer:

5. by newtons eq of motion

s =ut +1/2at^2

400 =1/2 a20×20

400 =1/2 a 400

a =2

force =mass ×acc

F = 7000×2

F =14000 N

6. by Newton eq of motion

v^2 - u^2 =2as

400= 2 a 50

400/100 =a

a = 4

by work energy theorem

1/2 m v^2 =F ×s

1/2 ×1×20×20= F 50

200÷50= F

F =4N