Question

a truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of 400m in 20s . find its acceleration. find the force acting on it if its mass is 7 tonnes (1 tonne=1000kg).​

Answer 1

Answer:

Explanation: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

= 14000 N

Answer 2

Answer:

Acceleration,a = 2ms^-2

Force,f = 1400N

Explanation:

Given :

Initial velocity of the truck,u => 0 [Since truck starts from rest]

Distance travelled,s => 400m

Time taken,t => 20s

Mass,m => 7 tonnes = (7 × 1000)kg = 7000kg

To Find :

Accelaration,a => ?

Force,f => ?

Solution :

We know that :-

\rm{s=ur+\dfrac{1}{2}at^2

\rightarrow\rm{400m=0\times 20s+\dfrac{1}{2}\times a\times(20)s^2

\rightarrow \rm{400m=0+\dfrac{1}{2}\times a\times400s^{2}

\rightarrow\rm{}400m=\dfrac{1}{1}\times a\times 200s^2→400m=

1

1

×a×200s

2

\rightarrow\rm{400m=a\times200s^2}→400m=a×200s

2

\rightarrow \rm{a=\dfrac{400m}{200s^2}

\rightarrow\rm{a=2ms^{-2}}→a=2ms

−2

Force = m × a

⇒ F = 7000kg × 2ms^-2

⇒ F = 1400N