Question

3. If a car moving a speed of 50m/s applies brakes and comes to rest in 3m, how long will the same car travel before coming to rest if its initial speed is 100m/s.

4. If a ball dropped from a tower falls down for 3s before hitting the ground, find the height of the tower. Also find the final velocity of the ball.

5. Raju travels half of the distance between 2 cities with a speed of 30m/s and remaining half
with speed 40m/s. Find the average speed and average velocity of Raju.

Pls answer these questions ​

Answer 1

Answer:

Explanation:

Answere 1;

given ;

a car moving a speed of 50m/s

here,

initial velocity of the car = 50 m/s

it applies brakes and comes to rest in 3m,

= 3 × 60 s = 180 s

final velocity of the car = 0 m/s [car stopped]

time taken by the car to stop after applying brakes = 180 seconds

now we have,

initial velocity(u) = 50 m/s

final velocity(v) = 0 m/s

time taken(t) = 60 seconds

so,

by the equation of motion

v = u + at

where a is the acceleration of the car

putting the values,

0 = 50 + a(180)

180a = -50

a = -50/180 m/s

a = -5/18 m/s

NOTE: negation of acceleration shows the retardation.

now,

given initial velocity(u) = 100 m/s

at the same retardation of the same car

here, we have,

initial velocity(u) = 100 m/s

acceleration(a) = -5/18 m/s²

final velocity(v) = 0 m/s [car will stop]

by the equation of motion

v² = u² + 2as

where,. S = distance travelled

putting the values,

(0)² = 100² + 2(-5/18)s

-10s/18 + 10000 = 0

-10s/18 = -10000

S = -10000 × 18/-10

S = 18000 m

so,

S = 18 km

so,

distance travelled by the car after applying brakes when initial velocity of the car will 100 m/s

= 18 km