Plz i need for the 5 problems. plz show the !

1. a car starts from rest and, after 10s, it is moving at 30 m/s. calculate the acceleration.

2. a truck is moving initially at 10 m/s and, after 8s, it reaches a final velocity of 22 m/s. calculate the acceleration.

3. a car accelerates at 5 m/s^2. assuming the car starts from rest, how much time does it need to accelerate to a speed of 15 m/s?

4. a car is moving with a constant velocity of 20 m/s for 10 seconds. what is its acceleration?

5. a shuttle bus comes to a sudden stop by applying the brake, it accelerates uniformly at -4.1 m/s^2 and it slows from 9.0 m/s to 0.0 m/s. find the time interval of the acceleration of the bus.

1.   3

2.   1.5

3.   3 seconds

4.   0

5.   2.2 seconds

Explanation:

(1)

From v= u + at where v is final velocity, u is initial velocity, a is acceleration and t is time.

Making a the subject we have

Substituting u=0 since it’s at rest, v=30m/s and t=10 seconds

a =

(2)

From v= u + at where v is final velocity, u is initial velocity, a is acceleration and t is time.

Making a the subject we have

Substituting u=10m/s, v=22m/s and t=8 seconds

a =

(3)

From v= u + at where v is final velocity, u is initial velocity, a is acceleration and t is time.

Making t the subject we have

Substituting u=0m/s since at rest, v=15m/s and a=5

=

(4)

When initial and final velocity are constant, there’s no acceleration as proven below

From v= u + at where v is final velocity, u is initial velocity, a is acceleration and t is time.

Making a the subject we have

Substituting u=20 since it’s at rest, v=20m/s and t=10 seconds

a =

(5)

From v= u + at where v is final velocity, u is initial velocity, a is acceleration and t is time.

Making t the subject we have

Substituting u=9m/s since at rest, v=0m/s and a=-4.1

=

its a 5.5 n

glad that