Question

. A truck starts from rest and Rolls down a hill with a constantacceleration. It travels a distance of 400 meter in 20 seconds. Find its

acceleration. Find the force acting on it if its mass is 7 metric tones.​

Answer 1

Answer:

• Acceleration of truck is 2 m/s²., and
• Force acting on it is 14 kilo-Newtons.

Explanation:

Given

• Mass of Truck, m = 7 metric tonnes

• Initial velocity of truck, u = 0 m/s

• Distance covered by truck, s = 400 m

• Time taken by stone to cover 400 m, t = 20 sec

To find

• Acceleration of truck, a = ?
• Force acting on truck, F =?

Formula required

• Second equation of motion

      s = u t + 1/2 a t²

• Expression for  Newton's second law  of motion

      F = m a

[ Where a is acceleration, s is distance covered, t is the time taken, u is initial velocity, F is the force applied, m is mass ]

Solution

Using second equation of motion

→ s = u t + 1/2 a t²

→ 400 = (0) (20) + 1/2 a (20)²

→ 400 = 0 + 1/2 a (400)

→ 400 = 200 a

→ a = 2 m/s²

Now,

Given mass of truck is

→ m = 7 metric tonnes

[ since, 1 metric ton = 1000 kg therefore ]

→ m = 7 × 1000 kg

→ m = 7000 kg

By newton's second law  of motion

→ F = m a  

→ F = ( 7000 ) · ( 2 )

→ F = 14000 N  = 14 kN

 

Therefore,

• Acceleration of truck is 2 m/s²., and
• Force acting on it is 14 kilo-Newtons.

Answer 2

$\bf \huge \{question \}$

A truck starts from rest and Rolls down a hill with a constantacceleration. It travels a distance of 400 meter in 20 seconds. Find its

acceleration. Find the force acting on it if its mass is 7 metric tones.

$\sf \bf \huge{solution }$

The truck starts from rest, so initial velocity = 0

Distance travelled = 400 m

Time taken = 20 s

We know the equation of motion, S = ut + ½ at2

400 = 0 + ½ a * (20)2

a = 2 m/s2

Now, mass = 7 metric tonnes

= 7 * 1000

= 7000 kg

So force = mass * acceleration

F = 7000 * 2

$\star \green {= 14000 N}$