Question

Question 3 (1 point) You are pulling a 4 kg object with 21 N at 60 degree with ground. What is acceleration? Your Answer units Answer Question 4 (1 point) A mover is pushing a 20 kg safe along a 30 degree ramp with 151 N force. What is the acceleration? Your Answer: Answer units Question 5(1 point) You are pulling a 2.8 kg object with 11.0 N force at 45 degree with ground which is frictional. If accelaration is measured 1.3 m/s2, what frictional coefficient? g-10m/s2 144 5 6 8 9 7

Answer 1

40" 20

Answer 2

SOLUTION :

3. 

Horizontal component of force applied to block of 4kg mass

= 21 cos (60)

= 21* 1/2

= 10.5 N

This horizontal force causes the block to move horizontally with an acceleration, say a m/sec^2.

So,

F = m a 

=> a = F/m

=> a = 10.5 / 4 

=> acceleration = a  = 2.625 m/sec^2 (ANSWER).

4.

Net force applied on the safe = 151 - 20*9.8 sin (30) = 53 N 

Acceleration = F/m  = 53 / 20 = 2.65  m/sec^2 (ANSWER).

5.

F = m a 

=> 11 cos(45) - µ * (2.8 * 9.8 - 11 sin45)   = 2.8  * 1.3 

=> 7.7782 - 19.66 µ = 3.64

=> µ = (7.7782 - 3.64)/19.66 = 0.21 

Coefficient of friction is = 0.21 (ANSWER)