Question

5. A truck starts from rest and rolls down a hill with a constant
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.)​

Answer 1

Answer:

...

Acceleration = 2m/s²...

F= ma= 7×1000×2= 14000N...

Explanation:

...

S= ut+1/2at²

S

400= 0×t+1/2a×20×20

1=0+1/2a

1=1/2a

a=2m/s²

F=ma

F=7×1000×2

F=14000N...

Answer 2

Answer:

• 14000 N

Explanation:

Given

• The mass of the truck, m = 7 tonnes = 7000kg
• The initial velocity of the truck, u = 0
• The distance covered by the truck, S=400m
• Time taken, t = 20 s
• Let a be the constant acceleration of the truck

Tofind

• Find its acceleration.
• Find the force acting on it if its
• mass is 7 tonnes

Solution

Using the second equation of motion

s = ut + ½ at²

Where,

• s = displacement
• u = initial velocity
• t = time
• a = acceleration

⇒ 400 = 0 × t + ½ × a × 20²

⇒ a = 400×2/20² = 2ms-²

Using Newton's second law of motion

F = ma

where,

• F = Force
• m = mass
• a = acceleration

⇒ F = 7000 × 2

⇒ F = 14000 N

Hence

• Acceleration = 2ms-²
• Force acting on the truck = 14000 N