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

=

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.