Question

1. A brick weighing 8.5kg is picked up to a height of 17m and dropped.
a. what is the weight of the brick?
b.Calculate the work done.

2. A car is traveling at 20m in 5s. The mass of the car is 15kg
Calculate the kinetic energy of the car​

Answer 1

Answer:

1. a) 8.5 kg

b) 1445 J

2. 30 J

I hope it's clear to you....

Answer 2

Solution :-

As per the given data ,

• Mass of the brick (m) = 8.5 kg
• Height (h) = 17 m
• Acceleration due to gravity (g) = 9.8 m/s ²

a . Weight of the brick (W)

We know that ,

➝ W = m x g

➝ W = 8.5 x 9.8

➝ W = 83.3 N

The weight of the brick is 83.3 N

b . Work done ( Wd)

➝ Wd = mgh

➝ Wd = 8.5 x 9.8 x 17

➝ Wd = 1416 J

The work done to lift the brick at a height of 17 m is 1416 J

2 .

• Distance traveled (s) = 20 m

• Time taken (t) = 5 s
• Mass of the car (m) = 15 kg

we know that ,

➝ v = d / t

➝ v = 20 / 5

➝ v = 4 m/s

Kinetic energy is the energy possesed by a body in motion

We know that ,

➝ KE = mv² / 2

➝ KE = 15  x 4 x 4 / 2

➝ KE = 15  x 8

➝ KE = 120 J

The kinetic energy of the car is 120 J